A how-to is an informal, often short, description of how to accomplish some specific task. They are generally meant to help non-experts, and may leave out details that are only important to experts, and may be greatly simplified from an overall discussion of the topic. See procedural knowledge for a discussion of what sort of knowledge is imparted, and how far it can be imparted, in how-tos.
Other types of instructional documentation include FAQs, manuals and guides. Wikipedia contains some procedural knowledge, partially listed below. For a list of how-tos related to Wikipedia itself, see Wikipedia:Help.
Note: You cannot search on the words "how" or "to" in the Wikipedia search. To view an alphabetical listing of How-tos, you can visit this Search Results page.
Computer How Tos
Science and Teaching
Life Sciences (including Food Production)
Language (and Geography/Culture?)
Literature (including Reference)