How to install Free SSL on Ubuntu Apache/Nginx using certbot?

1. Update repository for certbot installation
# sudo add-apt-repository ppa:certbot/certbot

2. Install certbot package for Apache/Nginx
# apt install python-certbot-apache    //For Apache Webserver
# apt install python-certbot-nginx    //For Nginx webserver

3. Check whether you have working virtual host configuration file of Apache/Nginx. Also check whether A records are updated and pointed to the server where you are installing SSL. If A record is not updated, SSL will not be installed.
# apache2ctl configtest    //To check apache configuration
# nginx -t        //To check Nginx configuration

4. Once step 3 is confirmed, run below command
# certbot –apache    //For apache webserver
# certbot –nginx    //For Nginx webserver

Provide email ID on which you will receive SSL expiration notifications. Also, set automatic redirection which is a good practice.