What is Switch to Desktop 1 and Switch to Desktop 2?

I have a feeling this is a very basic and simple question, so I am sorry if it is. If you know what this is, please do tell me!

;-)

I have just noticed that I have 2 desktops!! And I wonder why??

I have an iMac and I am using OS 10.10.3. I generally just do email and internet with some writing, organise my photos and music.

I was looking at the System Preferences, specifically the KEYBOARD Preference.

There are such things as Launchpad & Dock, Display and Mission Control etc. etc.

Under MISSION CONTROL, a lot of shortcuts are listed up.

I noticed there was a shortcut for "Switch to Desktop 1" and "Switch to Desktop 2"

I do not recall making such a shortcut and I do not know if it was always there. If it was always there, what is the purpose of having a shortcut to switch between two desktop screens?? Is it just a way to hide what you are doing by quickly changing to a different screen??

Can I make more Desktops? If I can do that, what would be the purpose? Could I have certain applications open on one desktop, but have other applications open on a different desktop making for an uncluttered working environment?? And then switch between Desktops depending what I am working on??

I looked around in the HELP files, but I have yet to find an explanation. I would really appreciate any help!