Writing for college assignments means you consult the work of others, then add your own take on that work.
Throughout your paper, project or presentation, as well as at the end, you will give credit to the sources you consulted. To NOT give credit to the authors of your sources is plagiarism.
You need to cite ALL content that comes from other sources: direct quotes from the author and also passages that you've summarized or paraphrased. You credit not only the author's words, but their thoughts and ideas as well.
Citing your sources lends credibility to your writing.
The citation style (AMA) defines HOW you give credit, but no matter what style you use, it's important that you do acknowledge where any thoughts, ideas, and words are not your own. AMA citations are generally used for writing about topics in medicine and health, but use the citation style your instructor requires, no matter what the field.