There are certain types of books that I more or less assume all readers read. (Novels, for example.)
But then there are books that only YOU read. Instructional manuals for fly-fishing. How-to books for spinning yarn. How to cook the perfect souffle. Rebuilding car engines in three easy steps. Dog training for dummies. Rewiring your house without electrocuting yourself. Tips on how to build a NASCAR course in your backyard. Stuff like that.
I read craft books, in particular quilting and embroidery, and books that focus on things that I collect, like Russian matryoshka dolls and all things Hello Kitty. I also like cookbooks that focus on baking.
With craft books and cookbooks, I don't so much read them as use them, although they are fun to page through and browse. There usually isn't much to actually read in a quilt book; there are some that cover aspects of quilting history but most are very standardized pattern books. The fun in "reading" pattern books is figuring out how to adapt one, or reading through the instructions to familiarize myself with a new technique. Good cookbooks can have a wealth of information apart from the recipes. One of my favorites is a baking book from the 1970s called The Breads of France; in addition to the recipes, this book has some great information on French regional culture and gastronomy. There's a whole beautiful country outside of Paris and I love this idiosyncratic travelogue/recipe stash.
I also have a small collection of foreign language dictionaries, which I collect when I travel, and books on cat health and books on hiking.