This document discusses folksonomy, which is a system of classification created by users tagging online items. It consists of users, tags, and resources. Users create tags to categorize and describe resources like web pages, photos, and videos. There are two types of folksonomy: broad, where multiple users can apply the same tag, and narrow, where each tag can only be used once. Social tagging allows users to collaboratively tag resources for knowledge acquisition. Folksonomies are used in many web applications and have advantages like being simple, flexible, and enabling discovery, but also have disadvantages like lack of control, precision, and consistency.