# What is SSL? Why does my site show a “Not secure” warning?

https://tiklaweb.net/en/knowledgebase/article/what-is-ssl-not-secure-warning

SSL (today TLS) is the technology that encrypts the connection between the browser and the site. When it is active a padlock appears in the address bar and the address starts with `https://`.

### Why it matters

- Passwords and personal data typed into forms cannot be read by third parties.
- Browsers mark unencrypted sites as “Not secure”.
- Search engines prefer sites that use HTTPS.

### Common causes of the “Not secure” warning

1. No SSL certificate is installed on the site.
2. The certificate has expired.
3. A certificate may be needed separately for the www and non-www address; one may be installed and the other missing.
4. The page is HTTPS but some images or files load over HTTP (mixed content).

### Steps to fix it

- Enable the SSL certificate for your domain in your hosting panel.
- Redirect HTTP requests to the HTTPS address.
- For mixed content, replace `http://` links in the page source with `https://`.
- Make sure the certificate renews automatically.