The modern encyclopedia was developed from the dictionary in the 18th century. Historically, both encyclopedias and dictionaries have been researched and written by well-educated, well-informed content experts, but they are significantly different in structure. A dictionary is a linguistic work which primarily focuses on alphabetical listing of words and their definitions. Synonymous words and those related by the subject matter are to be found scattered around the dictionary, giving no obvious place for in-depth treatment. Thus, a dictionary typically provides limited information, or background for the word defined. While it may offer a definition, it may leave the reader lacking in understanding the meaning, significance or limitations of a term, and how the term relates to a broader field of knowledge.