Failing to cite your sources equates to plagiarism. Plagiarism is a serious thing that is totally, completely, 100% preventable. You just need to give credit where credit is due. - easybib.com
There are several different styles/formats for citing sources in a paper. Your instructor will generally have a preferred style to use in your paper, and will tell you which one he/she is requiring for your assignment. Common citation styles include:
Note: Properly cited material will contain both an in-text citation (or footnote), as well as the full citation in the references section. An in-text citation is an abbreviated citation immediately following the quotation or paraphrase of the original source. Generally, anything cited in your text must also show up on your reference page and vice versa! [Image Credit]