An encyclopedia is a comprehensive reference work that provides information on a wide range of topics. It is organized alphabetically and contains articles that summarize knowledge in various fields, such as science, history, and culture. Encyclopedias can be found in print or online, making them accessible to anyone seeking information. These resources are often written by experts and are designed to be reliable and factual. Popular examples include Encyclopedia Britannica and Wikipedia. Encyclopedias serve as valuable tools for research, education, and general knowledge, helping users learn about the world around them.