Citations and references are necessary for all papers that include a research component.
Any fact, figure, or idea that did not come from you must have both an in-text citation and an end reference.
Without proper citations, you are committing plagiarism, which is a kind of academic dishonesty.
Plagiarism is the practice of pulling ideas from other sources to include in your own work without giving them credit. This kind of intellectual theft, whether it was intentional or not, comes with academic consequences.