The document discusses different types of dictionaries including: unabridged dictionaries which contain over 265,000 words and cover word histories and usages; abridged dictionaries which contain 150,000-250,000 words and focus on common words; reduced word dictionaries containing under 60,000 words; specialized dictionaries focused on a specific topic like American regional English or crossword puzzles; etymological dictionaries tracing word development over time; slang dictionaries defining informal terms; synonym and antonym dictionaries; dictionaries of abbreviations and acronyms; subject dictionaries explaining terms in specific fields; foreign language dictionaries; biographical dictionaries providing information on people's lives; and retrospective biographical dictionaries providing historical biographical information. Examples are given for each type