Security threats like data theft etc are on the rise amp it is of utmost importance that we employ some security to avoid such incidents. This is especially true when we are trying to access some websites over the public internet amp our connections are not secure.
To avoid such unencrypted data transfers we use SSL certificates. SSL or Secure Socket Layer is a protocol that is used for securing encrypt our website traffic. This avoids data theft even if the data would have been intercepted by a 3rd party it will be useless to them as the encryption used to secure the traffic is quite strong.
SSL certificates are of such importance that now almost all web browsers show a warning when we are visiting a website that does not have a valid SSL certificate in use.
The SSL certificate that is used to secure the websites on the Public internet uses SSL certificates that are signed by Certification Authorities CA like Comodo GeoTrust Symantec etc amp they charge a fee for that. And then there are CAs like Lets Encrypt which provide SSL certificate for free but for a lesser duration.