Final answer:
An encyclopedia is a reference book that summarizes information from all branches of knowledge, providing background information and basic facts. Encyclopedias are secondary sources which compile and summarize information from various credible sources, and substantial encyclopedias like the New Encyclopædia Britannica are often multi-volume for thorough coverage.
Step-by-step explanation:
A reference book providing summaries of information from all branches of knowledge is called an encyclopedia. Encyclopedias are designed to consult general reference works to gain background information and basic facts on a wide range of topics. These summaries, overviews, and definitions in general reference works can assist in deciding whether to explore a topic further and which sources to consult next for detailed information.
Some well-known examples of encyclopedias include the Random House Encyclopedia and the Columbia Encyclopedia, which give brief overviews. For more extensive information, larger works like the New Encyclopædia Britannica are available which contain detailed information across many volumes and also provide online access.
Encyclopedias act as secondary sources by evaluating published work rather than presenting original research. Their value lies in the compilation, comparison, and summation of information from a variety of credible sources. To enhance further study, a compact bibliography is often included to recommend additional readings. Due to the comprehensive nature of the material, some encyclopedias are offered in multiple volumes for flexibility and efficiency.