All professional writing must be clear, concise and avoid plagiarism. It is important to tell the reader what ideas are unique to the author and what came from other sources.
Document styles such as MLA, APA and Chicago provide a consistent format to help the reader understand your arguments and find the supporting literature references. Style allows for readers to cross-reference sources easily, provides a consistent format within the discipline of study and helps protect against plagiarism. Sloppy or missing formatting reduces credibility as an author and will weaken the written argument. Some readers may stop reading if the format makes the paper difficult to read. Remember styles are more than just references, it includes grammar, spelling, verb usage, voice and format of delivered information.
Citation management tools allow a user to organize and retrieve information, such as citations for books, articles, and Web sites, by interfacing with library databases. The citation manager has a citation formatting software that works with word-processor (MS Word) to insert properly formatted footnotes or citations into a paper and create a properly formatted bibliography. Citation managers not only help you write a properly formatted paper, but the software will allow you to quickly switch between hundreds of format styles (MLA -> APA) with the click of a button.
These programs are "GARBAGE IN - GARBAGE OUT". If the reference information is incorrect in the citation manager, the output reference in the paper will also be incorrect!
Reference management software does not do the same job as a bibliographic database, which tries to list all articles published in a particular discipline or group of disciplines (PubMed, PsycINFO). These databases are large and are hosted on large banks of servers which cost a lot of money and take technical skill to maintain. Reference management software collects a much smaller dataset of the publications that have been used or are likely to be used by a particular author or group, and are housed on an individual's personal computer.
There are many companies that produce citation management software. Here are a few examples. Explore these links and compare features.