Published: 26.08.2026
An SSL/TLS certificate encrypts the connection between a visitor and your website and proves the identity of the site. Browsers mark sites without it as "not secure", and search engines prefer HTTPS.
What does a certificate do?
- Encrypts data such as passwords and card details.
- Protects against tampering on the way.
- Confirms that the visitor is connected to the real domain.
Validation levels
- DV (Domain Validation): checks only that you control the domain. Issued in minutes, ideal for most sites.
- OV (Organization Validation): also verifies the company. Suitable for business portals.
- EV (Extended Validation): the strictest check of the legal entity. Modern browsers no longer show a special bar, so the visible benefit is small.
Single, wildcard and multi-domain
- A single certificate covers one hostname.
- A wildcard covers all subdomains, for example
*.example.com. - A multi-domain (SAN) certificate covers several different names.
Let's Encrypt
A free certificate authority that issues DV certificates valid for 90 days. Renewal is automatic with the right software, so it is a great choice for most websites.
How to install
- Generate a request or use the automatic tool in your control panel.
- Prove control of the domain by a file or a DNS record.
- Install the certificate and the chain on the web server.
- Redirect HTTP to HTTPS and fix mixed content.
Common problems
- An expired certificate: set up automatic renewal and monitoring.
- A name mismatch: the certificate does not include the exact hostname.
- A missing intermediate certificate in the chain.
- Mixed content, when images or scripts are still loaded over HTTP.
Frequently asked questions
Do I need a paid certificate? For most sites a free DV certificate is enough. Choose OV for formal trust requirements.
