"The central function of a legal citation is to allow the reader to efficiently locate the cited source."
Source: The Bluebook: A Uniform System of Citation (Columbia Law Review Ass'n et al. eds., 19th ed. 2010).
1. Helps the reader to find more information or to locate the work cited.
2. Gives the writer credibility. Is the work well researched? Did you cite the critical authorities relevant to your issue?
3. Helps the writer avoid plagiarism. You must give credit to the creator of the information. Conversely, you cannot claim credit for something you did not create.
Your opinions, your ideas and your work
Generally Accepted Facts
The most recent version of the Bluebook (The 20th edition) was published in June, 2015. Some of the sources below pre-date the latest version of the Bluebook, but are still useful. You may want to keep in mind what has changed from the 19th edition (published in 2010). The 20th edition includes some new material in Rule 18, which governs the citation of electronic resources, among other changes. For a list of changes, see List of differences between the 19th and 20th editions by law librarian Janelle Beitz or Changes to the 20th Edition of the Bluebook by law librarian Cynthia Pittson.
All software products (including Lexis and Westlaw) make mistakes when converting to Bluebook format. You must double check all citations. Ultimately you are responsible for correctly writing the citation in Bluebook format, not the software.