Creating a subdomain in NameCheap is pretty straight forward. These instructions are for NameCheap shared hosting customers. Subdomains can be used for all kinds of reason and are a way to have seperate sections of your website without having to purchase another domain name.
You want to first log into NameCheap cPanel.
Once logged in, look for "Domains". Click on "Subdomains" and type in your subdomain name under "Create a Subdomain" box. For example mail.
Under "Domain" choose which domain name you want to add a subdomain for. For example anetcomputers.com. Type in the path to your website files under "Document Root".
For example /public_html/mail. Finally, click on a "Creat" button. You have now just created a subdomain mail.anetcomputers.com with a document root of /public_html/mail. You can now install whatever type of website software in /public_html/mail.
As an added bonus, NameCheap allows you to install free sofware with there softaculous tool. What this means is that you can install a wide array of software with there easy basically one click installs. You can even install seperate versions of the same software this way.
For example I have email service with AnetComputers.com. I could have installed RoundCube mail using mail.anetcomputers.com to access. This would be seperate email from my main AnetComputers.com email service.
You can even install a seperate WordPress Content Management System with subdomains. With Softaculous, I could have created blog.anetcomputers.com with /public_html/blog document root directory. Then I could have installed WordPress on this subdomain.
This blog would then be completely seperate from my main blog at AnetComputers.com. Subdomains can be very useful and possibly save you money. Also, perhaps you can use subdomains to test out certain types of websites before you go live with them.
You could even use subdomains for development purposes. Subdomains are considered completely seperate and diffirent websites. Hopefully, this tutorial was productive and helped you create a subdomain on NameCheap shared hosting using cPanel.