# What is SSL certificate?

> An SSL certificate is a small digital file that proves your website is genuine and lets it use HTTPS, so information sent to and from it is encrypted.

- Source: https://nerdsharks.com/glossary/ssl-certificate
- Publisher: Nerdsharks (Exeter, Devon, UK)
- Updated: 2026-09-26

Also called: SSL, TLS certificate, TLS, security certificate, padlock.

An SSL certificate is issued by a trusted organisation, called a certificate authority, confirming that a domain belongs to whoever runs the website. It lets the site use HTTPS, which scrambles data travelling between the visitor and the site.

Most small business websites use a free certificate from a service such as Let's Encrypt, installed and renewed automatically by the host. Paid certificates exist but offer no extra padlock or trust for an ordinary business website.

Technically the modern technology is called TLS (Transport Layer Security), but everyone in the industry, hosts and browsers included, still says SSL.

## Why it matters for a small business

Without one, browsers label your site ‘Not secure’, which puts off customers, especially on a contact form. There is no reason to pay extra for an ordinary business site: a free, automatically renewing certificate does the same job.

**Example:** A café's booking page shows ‘Not secure’ in Chrome because the certificate was never installed. The host adds a free one and the warning disappears.