What is mulching?

I've just started gardening this year - and I must confess: I'm completely blind in this area, so I need a lot of coaching/training/education about what to do and how to do in order to get the perfect looking garden.

Here is my first big question mark: what is mulching?

So, organic mulch can described as: shredded leaves, dried grass clippings, cocoa shells, buckwheat hulls, shredded bark or wood chips, and finished compost.

These guys here have a complete guide on mulching. Here are the mulch types they describe:

• shredded bark
• leaves
• grass clippings
• straw
• compost
• pine needles
• pine bark nuggets
• wood chips
• cocoa hull mulch
• gravel or river rock.

I just realized that I've bought some foil that could do just fine for mulching (at least for my hedge) - but did not use it, as I could not see its utility. Now it looks like it could be the solution to all the weeds that have grown around...