What are recipes and how to create one ?

Hello all.

Sorry for this dummies question but I don't really understand what are recipes and how are they created ?

I created some content types and personalized blocks, images, and some specifics css. Can I put all this in a recipe ? And how to create it ?

Sorry if the question is "stupid" but i'm quite sure it's a super cool feature and i really love the idea i can create somes ?

 

Thanks for your help.

Dominique.