What Is an SSL Certificate? HTTPS Explained Simply
Learn what an SSL certificate does, how HTTPS encryption works, the five types of SSL certificates, how to get a free SSL certificate with Let’s Encrypt, and why HTTPS directly affects your Google rankings and AdSense eligibility.
When you see a padlock icon in your browser’s address bar, an SSL certificate is behind it. SSL certificates secure the connection between your website and its visitors, encrypt the data travelling between browser and server, and verify that the site is who it claims to be. In 2026, an SSL certificate is not optional: it is a requirement for Google search rankings, Google AdSense approval, and user trust. This guide explains everything you need to know.
What Is an SSL Certificate?
An SSL certificate is a digital certificate that does two things: it authenticates the identity of a website and it enables an encrypted connection between a web browser and a web server. When a website has a valid SSL certificate installed, its URL begins with HTTPS instead of HTTP. The S stands for Secure.
Certificate Authorities (CAs) are the organisations that issue SSL certificates. Before issuing a certificate, a CA verifies that the applicant actually controls the domain. This verification process is what makes HTTPS trustworthy: when your browser sees a valid certificate for example.com, it has been verified by a trusted third party that the server you are talking to actually belongs to example.com, not an attacker pretending to be that site.
An SSL certificate is not just encryption. It is a verified, third-party guarantee that you are connected to the real website and not an impostor. Without it, your users have no way to know who they are really talking to.
SSL vs TLS: What Is the Difference?
Technically, the protocol is now called TLS (Transport Layer Security), not SSL (Secure Sockets Layer). SSL was the original protocol, developed in the 1990s. It was replaced by TLS 1.0, then TLS 1.1, TLS 1.2, and now TLS 1.3 as the current standard. The old SSL protocol has known vulnerabilities and is no longer used or supported by modern browsers.
Despite this, everyone still calls the certificates “SSL certificates” because the term stuck. When a hosting provider offers you a “free SSL certificate,” they are providing a TLS 1.3 certificate. The certificates themselves are the same: it is only the naming convention that has not caught up with the protocol evolution. Do not let the terminology confusion stop you: when you need an SSL certificate for your website, install one and it will use TLS automatically.
What SSL Certificates Actually Do
An SSL certificate provides three distinct security properties, each solving a different attack scenario that would otherwise be trivially easy for an attacker on the same network:
How HTTPS Encryption Works: The TLS Handshake
Every time your browser connects to an HTTPS website, it performs a “TLS handshake” before any data is exchanged. This process establishes a secure, encrypted channel in milliseconds. Understanding the handshake explains why HTTPS is so secure and why a valid SSL certificate is a necessary part of it:
HTTP vs HTTPS: A Complete Comparison
The difference between HTTP and HTTPS is not just a padlock icon. It affects security, search engine rankings, browser behaviour, user trust, and AdSense eligibility. Here is the full picture:
| Factor | HTTP | HTTPS |
|---|---|---|
| Connection | Unencrypted — plain text | Encrypted with TLS |
| Data in transit | Readable by anyone on the network | Readable only by sender and intended server |
| Authentication | None — no way to verify the site is real | Certificate Authority verified domain ownership |
| Data integrity | Content can be modified in transit | Tampering is detected and rejected |
| Browser indicator | “Not Secure” warning in Chrome and Firefox | Padlock icon in address bar |
| Google search ranking | Penalised relative to HTTPS equivalents | Confirmed positive ranking signal since 2014 |
| Google AdSense | Not eligible for AdSense approval | Required for all AdSense sites |
| Browser APIs | Geolocation, camera, push notifications blocked | All modern browser APIs available |
| Cost | Free (no certificate needed) | Free with Let’s Encrypt |
The Five Types of SSL Certificates
SSL certificates differ in how thoroughly the Certificate Authority verifies the applicant’s identity before issuing the certificate, and in how many domains they cover. Choosing the right type of SSL certificate depends on your site’s purpose and scale:
The simplest and fastest type of SSL certificate. The Certificate Authority verifies only that the applicant controls the domain, typically by placing a file on the server or adding a DNS record. No organisation details are checked. Issued in minutes.
The CA verifies the domain and the legal existence and status of the organisation. More trustworthy than DV because it confirms a real business is behind the site. Takes 1 to 3 business days to issue.
The most rigorous validation. The CA verifies domain ownership, legal organisation existence, physical location, and operational status. Historically displayed a green company name in the address bar, though modern browsers now treat EV and OV certificates identically visually.
Covers the main domain and all of its first-level subdomains with a single certificate. A wildcard certificate for *.example.com automatically covers shop.example.com, blog.example.com, api.example.com, and any new subdomain you create. Manage one certificate instead of many.
Subject Alternative Names certificates cover multiple specific different domains in a single certificate. A single SAN certificate can cover example.com, example.net, another-domain.com, and api.third-site.org simultaneously.
How to Get a Free SSL Certificate for Your Website
In 2026, there is no reason to pay for an SSL certificate for a standard website. Let’s Encrypt, a free and automated Certificate Authority backed by major tech companies, provides free SSL certificates to any domain owner. Every major hosting provider now integrates Let’s Encrypt directly into their control panel.
Getting a free SSL certificate takes under five minutes on most hosting platforms. Here is how to do it on the most common providers:
- Log in to hPanel
- Go to Hosting, select your plan
- Find SSL in the left menu
- Click Install SSL for your domain
- Done, usually active within minutes
- Log in to your hosting control panel
- Look for Security or SSL/TLS section
- Select your domain
- Click Install Free SSL or Let’s Encrypt
- Wait up to 24 hours for DNS propagation
- SSL is automatic — no action needed
- Every deployed site gets HTTPS by default
- Custom domains get free SSL certificates automatically
- Certificates auto-renew before expiry
- Install Certbot: sudo apt install certbot
- Install the Nginx or Apache plugin
- Run sudo certbot –nginx -d yourdomain.com
- Certbot configures HTTPS and auto-renews
Installing a Free SSL Certificate With Let’s Encrypt and Certbot
For developers running their own Linux servers (VPS or dedicated), Certbot is the standard tool for obtaining and automatically renewing Let’s Encrypt SSL certificates. It installs the certificate, configures your web server, and sets up automatic renewal before the 90-day expiry:
When you install Certbot on Ubuntu or Debian, it automatically creates a cron job or systemd timer that attempts certificate renewal twice per day. Let’s Encrypt certificates expire after 90 days, but Certbot begins renewal attempts when 30 days remain. In practice, certificates renew automatically without any manual intervention. Verify your renewal is working by running sudo certbot renew –dry-run and confirming it reports no errors.
Why SSL Certificates Directly Affect SEO and Google AdSense
Getting an SSL certificate for your website is not just a security decision. It directly determines whether your site ranks in Google search results, whether it qualifies for Google AdSense monetisation, and whether users trust it enough to stay. These are three concrete, measurable reasons to prioritise HTTPS:
Installing an SSL certificate on your hosting makes HTTPS available, but if your site still serves content on HTTP without redirecting, Google may index the HTTP version. Ensure your server redirects all HTTP traffic to HTTPS with a 301 redirect. Most hosting control panels have a “Force HTTPS” toggle. For Nginx, add return 301 https://$host$request_uri; in your HTTP server block. For Apache, add Redirect permanent / https://yourdomain.com/ in your .htaccess file.
SSL Certificate Expiry: What Happens When a Certificate Expires
SSL certificates are not permanent. Every certificate has an expiry date, after which browsers will show a full-page security error to every visitor, completely blocking access to the site. Understanding certificate lifetimes and renewal is critical for any site owner:
When an SSL certificate expires, every browser shows a full-page blocking warning to every visitor: “Your connection is not private” or “Warning: Potential Security Risk Ahead.” Most users will not proceed past this warning. Traffic drops to near zero until the certificate is renewed. This is avoidable entirely with auto-renewal configured.
Click the padlock in your browser’s address bar on any page of your site and look for the certificate expiry date. If it expires within 30 days and auto-renewal is not confirmed, renew it manually immediately. Many production outages are caused by expired SSL certificates on servers where auto-renewal was set up but silently stopped working. Verify renewal is actually happening, not just configured.
7-Step Guide: Setting Up HTTPS on Your Website
Follow this sequence to go from an HTTP site to a properly configured HTTPS site with automatic renewal, correct redirects, and verified search engine and AdSense readiness:
- Choose and obtain your SSL certificate. For most websites, a free Let’s Encrypt certificate through your hosting control panel is the correct choice. Log in to your hosting control panel, find the SSL section, and install the certificate for your domain. If your hosting does not offer Let’s Encrypt integration, use Certbot directly on your server. For sites requiring organisation validation, purchase an OV certificate from a trusted CA such as DigiCert, Sectigo, or Comodo.
- Verify the certificate is installed correctly. After installation, visit your site using the https:// prefix. You should see a padlock in the address bar. Click the padlock to confirm it shows a valid certificate for your domain with a future expiry date. If you see any security warnings, the installation has a problem that needs to be resolved before proceeding.
- Set up HTTP to HTTPS redirects (301 redirects). The SSL certificate makes HTTPS available, but does not automatically redirect HTTP traffic. Configure a 301 permanent redirect so that any visit to http://yourdomain.com is immediately redirected to https://yourdomain.com. Most hosting control panels have a “Force HTTPS” toggle. This is required for both SEO (301 redirects pass link equity) and AdSense compliance.
- Fix mixed content warnings. If your site loads over HTTPS but some resources (images, scripts, stylesheets, fonts) are still loaded over HTTP, browsers show a mixed content warning and may block the HTTP resources. Search for http:// in your HTML, CSS, and JavaScript and replace with https:// or protocol-relative URLs (//). WordPress sites can use the “Better Search Replace” plugin to fix database-stored HTTP URLs in bulk.
- Update your sitemap and Google Search Console. If your site was previously indexed as HTTP, update your XML sitemap to use HTTPS URLs and resubmit it in Google Search Console. Add the HTTPS version of your site as a separate property in Search Console (Google treats HTTP and HTTPS as different sites). Monitor the Index Coverage report to confirm Google is indexing the HTTPS version correctly.
- Verify auto-renewal is working. For Let’s Encrypt certificates, run sudo certbot renew –dry-run to confirm Certbot can renew successfully. For hosting panel certificates, check whether auto-renewal is enabled in the SSL settings. Set a calendar reminder to check the certificate expiry date every 60 days regardless of auto-renewal, because renewal processes can fail silently.
- Reapply for Google AdSense if previously rejected. If your site was rejected from AdSense due to missing HTTPS, complete the setup steps above and wait 24 to 48 hours for Google to re-crawl your pages over HTTPS. Then resubmit your AdSense application. Ensure every page that Google can reach is served over HTTPS, including your privacy policy and about pages, as partial HTTPS coverage can still result in rejection.
Frequently Asked Questions About SSL Certificates and HTTPS
Yes, for encryption strength. The encryption provided by a free Let’s Encrypt Domain Validated certificate is identical to a paid certificate: both use the same TLS 1.3 protocol and modern cipher suites. The difference between free and paid certificates is not encryption quality but validation depth. A paid OV or EV certificate has had the issuing organisation’s identity verified by the CA, which means browsers can confirm a real business is behind the domain. For blogs, content sites, and most business websites, a free Let’s Encrypt DV certificate provides complete security. For banks, financial services, and high-value e-commerce, OV or EV provides an additional layer of verifiable organisational identity.
Yes. Google confirmed HTTPS as a positive ranking signal in 2014 and has since increased its weight in the ranking algorithm. In competitive search results, HTTPS is a tiebreaker that consistently favours the secure site over an equivalent HTTP site. For new sites, launching with HTTPS from day one means never competing at a structural disadvantage. For existing HTTP sites, migrating to HTTPS with correct 301 redirects transfers all existing link equity to the HTTPS version and provides the ranking benefit. The migration must be done correctly: incorrect redirects can temporarily reduce rankings, so following the 7-step guide above is important.
Google requires HTTPS for all AdSense publisher sites because ads are loaded via JavaScript that executes in the context of your page. Serving ads over an unencrypted HTTP connection creates a mixed content security problem and exposes ad traffic to interception. Google also requires HTTPS as a quality signal: AdSense is a premium advertising network and serving ads on HTTP sites would devalue the network by associating it with less professional or maintained websites. All sites in the AdSense publisher network must serve content over HTTPS, and this is a hard requirement checked at the time of application review and on an ongoing basis.
The moment a certificate expires, every major browser shows a full-page blocking error to every visitor. Chrome shows “Your connection is not private” with a red warning icon. Firefox shows “Warning: Potential Security Risk Ahead.” Most users will not click past these warnings. Traffic drops immediately and effectively to zero until the certificate is renewed. Search engines that cannot crawl an HTTPS site due to a certificate error may also begin deindexing pages. The solution is to renew the certificate immediately. For Let’s Encrypt certificates managed with Certbot, run sudo certbot renew. For hosting panel certificates, manually trigger renewal in the SSL settings. The site returns to normal within minutes of a successful renewal.
A wildcard SSL certificate covers your main domain and all of its immediate subdomains with a single certificate. A certificate for *.example.com automatically covers shop.example.com, blog.example.com, api.example.com, and any other subdomain you create, without requiring a separate certificate for each. You need a wildcard certificate if you run multiple subdomains (for example, separate subdomains for your shop, blog, and API). If you only have a single domain or a small fixed set of domains, standard DV certificates for each are simpler and cost the same with Let’s Encrypt. Wildcard certificates require DNS validation rather than file-based validation, which makes automated renewal slightly more complex but fully supported by Certbot.
This is a mixed content problem. Your page is served over HTTPS, but some resources on the page (images, scripts, stylesheets, iframes, or media files) are still loaded from HTTP URLs. The browser treats this as a security issue because the encrypted page is loading unencrypted content that could have been tampered with. To fix it: open your browser’s developer tools Console tab and look for mixed content warnings — they show the exact URL of the HTTP resource causing the problem. Replace all http:// URLs in your HTML, CSS, and JavaScript with https://. For WordPress sites, use the Better Search Replace plugin to find and replace all HTTP URLs stored in the database. After fixing, verify there are no remaining mixed content warnings by checking the Console tab on each affected page.
Tools for building and maintaining your website
Format JSON API responses, compare content between pages, convert data formats, generate URL slugs, and more. All free, all in your browser, no login required.
Install SSL Today. Your Rankings, AdSense, and Users Depend on It.
An SSL certificate is no longer optional for any website in 2026. Google requires HTTPS as a ranking signal for search results, Google AdSense requires HTTPS as a hard eligibility requirement, and every major browser shows a “Not Secure” warning for HTTP sites that actively drives users away. The good news is that getting a free SSL certificate with Let’s Encrypt takes under five minutes on most hosting platforms and costs nothing.
The five certificate types give you options for every situation: free DV certificates for blogs and personal sites, OV for business websites that benefit from verified organisational identity, wildcard certificates for multi-subdomain deployments, and SAN certificates for organisations managing multiple domains. Start with a free Let’s Encrypt DV certificate and upgrade only if your specific use case requires the additional validation.
Once your SSL certificate is installed, force HTTPS redirects, fix any mixed content warnings, update your Google Search Console property, and verify auto-renewal is working. These seven steps take less than an hour and put your site in full compliance with Google’s requirements for both search rankings and AdSense monetisation. Do it once, confirm it is working, and it takes care of itself.