A citation generator or "machine" searches for the publication information of your source from across the web and crafts a citation or Works Cited entry for you based on this information. There any many different ones available, but if you decide to use one, know that no online citation tool or software is perfect. They could give you the citation in a different style than the one you need. They could find the wrong publication information for the source you are using. If you enter incorrect information or do not include some information, then the citation they create will be incorrect.
Some sources provide their own citation. The library's databases may also provide citations for sources you find in them. These should only be used as a starting point, as they may not be entirely accurate, either. They often include too much information or are formatted incorrectly (they might be missing hanging indents, italicization, or double-spacing).
It is up to you to check the accuracy of your citations before submitting research papers or other class assignments.
Citations are used to identify the sources included in your research paper and provide the information needed to locate them.
Citations also give credit to the authors whose ideas you used to support the arguments in your paper. Failure to give credit to the sources you use is considered plagiarism and can result in a penalty against your work.