This document discusses compound words, which are words made up of two smaller words. Compound words can be understood by knowing the meanings of the individual words, such as "bluebird" meaning a bird that is blue. However, some compound words do not directly relate to the definitions of the words that comprise them, like "butterfly" or "hotdog". There are also different types of compound words including closed compounds without spaces, open compounds with spaces, and hyphenated compounds. The document was prepared by a student as an example of different compound word types and structures.