Creating a sub domain in NameCheap is pretty straight forward. These instructions are for NameCheap shared hosting customers. Sub domains can be used for all kinds of reasons and are a way to have separate 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 "Sub domains" and type in your sub domain name under "Create a Sub domain" box. For example mail.
Under "Domain" choose which domain name you want to add a sub domain 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 "Create" button. You have now just created a sub domain 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 software 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 separate 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 it. This would be separate email from my main AnetComputers.com email service.
You can even install a separate WordPress Content Management System with sub domains. With Softaculous, I could have created blog.anetcomputers.com with /public_html/blog document root directory. Then I could have installed WordPress on this sub domain.
This blog would then be completely separate from my main blog at AnetComputers.com. Sub domains can be very useful and possibly save you money. Also, perhaps you can use sub domains to test out certain types of websites before you go live with them.
You could even use sub domains for development purposes. Sub domains are considered completely separate and different websites. Hopefully, this tutorial was productive and helped you create a sub domain on NameCheap shared hosting using cPanel.