A certificate guarantees that the data communication you offer to your website visitors is classified as secure. This creates trust among your visitors while also ensuring that their data does not end up in the wrong hands. 

Certificates can be characterized by a number of attributes, including browser acceptance, the type of validation used, and the number of domains a single certificate can protect. In general, the following rule of thumb applies: Certificates with simplistic validation methods are often less secure. Accordingly, these certificates may not be accepted by every browser. Modern browsers, including those used by mobile devices (e.g., iPad, iPhone, Android devices, etc.) will frequently display a warning when accessing a website with an insecure certificate.

You can find out how to add a certificate to your web hosting at: SSL Encryption with Let’s Encrypt