What is Quota?

I was just wondering what Quota is. I was just looking under properties under my local drive C when i saw Quota. What is it for and is it something i should have on for ignore?

Quotas are used to limit a user account's hard drive usage. If a user reaches their quota limit, they are no longer able to write files to the directory in which they have a quota.

Quotas are used extensively in Novell networks, and Microsoft networks where the workstation is part of a domain, and therefore logs into a domain controller.

makes sense