Answers (1)
You don't say, but I have to assume you are talking about making a pie. You don't have to use a crust at all, but if you do, some crusts requiring baking before filling, and some don't.
There are lots of different recipes for crusts. If you want a very flaky crust, you use lard. If you want a very tasty crust, you use butter. If you want a very crisp crust, you use shortening. The very best crusts are made with vodka instead of water. Or maybe you want a crumb crust, in which case no instructions are needed.
You can use google.com to search for kitchen science and there is a lot of it.
"The Best Apple Pie": www.backwoodshome.com/articles2/blunt132.html
Cookie science: sweets.seriouseats.com/2013/12/the-food-lab-the-best-chocolate-chip-cookies.html