Citations and bibliographies are the mechanisms through which attribution is accomplished. One example you may be familiar with is Wikipedia. Each fact in the encyclopedia must have a corresponding citation, so that others can confirm the accuracy of the information, as well as know where to go to learn more. Below is a snippet of a Wikipedia article on the tapir, alongside the corresponding references from the end of the article. Click the pictures to explore the article yourself!
NOTE: Although we've used Wikipedia as an example of citations, remember that most professors do not allow you to cite to Wikipedia in your scholarly papers. This is in part because scholarly writing almost never cites background information, which is what Wikipedia provides. Also remember that anyone can edit a Wikipedia article so, while you can refer to an articles' citations, you should verify information found in a Wikipedia article by confirming it in other authoritative (scholarly) sources.