Chrome and Firefox have started showing insecure warnings on sites without SSL certificates. Without SSL, your website will show insecure to the visitors. Therefore, using an SSL-encrypted connection for safety, accessibility or PCI compliance reasons is necessary. It becomes very important to redirect from HTTP to HTTPS.
What is SSL?
SSL (Secure Sockets Layer) is a standard security protocol for establishing encrypted links between a web server and a browser in an online communication.
The usage of SSL technology ensures that all data transmitted between the web server and browser remains encrypted.
An SSL certificate is necessary to create SSL connection. You would need to give all details about the identity of your website and your company as and when you choose to activate SSL on your web server. Following this, two cryptographic keys are created — a Private Key and a Public Key.
In order to force your web traffic to use HTTPS, edit the codes in the .htaccess file.
Before we move onto redirecting HTTP to HTTPS, here’s how you can edit .htaccess file. If you already know skip to Redirection steps.

//
Source