multiple WordPress installations?

Hello,
I’m a website designer and am new to WP. Can I install WordPress in multiple folders on my hosting company’s server so that when I build sites for customers we can see them live in a test environment first? That is, let’s say my personal domain name is janedoe.com. I would create janedoe.com/mary_smith and janedoe.com/john_black for each of those customers, and install WordPress in each of those folders so that I could build both customer’s sites simultaneously. Is this possible, or does WP place files in the root directory of my server that would get garbled if I tried to do this? Thanks!