How to Cite Sources: A Complete UK Guide (2026)

To cite sources, you acknowledge every idea, quote or fact you borrow with two linked parts: a short in-text citation in your writing and a full entry in a reference list or bibliography at the end. You do this in the referencing style your university requires – usually Harvard, APA, MLA, OSCOLA, IEEE or Vancouver. Citing correctly protects you from plagiarism and earns easy marks.

Key takeaways

• Citing has two parts: an in-text citation and a full reference.
• You must cite quotes, paraphrases, data, images and ideas that are not your own.
• Use the one style your course requires, consistently.
• Author–date styles (Harvard, APA) differ from numeric styles (IEEE, Vancouver).
• Good citing prevents plagiarism and shows the depth of your research.

What does it mean to cite a source?

To cite a source is to give credit to where information came from. The in-text citation flags the borrowed material at the exact point you use it, and the matching reference gives full publication details so a reader can find the original. Knowing how to cite sources is a core academic skill in every UK degree.

Why is citing sources important?

Citing sources avoids plagiarism, which can mean losing marks or failing. It also builds credibility by showing your argument rests on real evidence, and it lets markers and readers trace your research. Strong, consistent citation is one of the simplest ways to lift an essay’s grade.

How do you cite sources in each referencing style?

The method depends on the style. We have a full UK guide for each:

• Harvard / APA (author–date): see our APA referencing guide.
• MLA (humanities): see our MLA referencing guide.
• OSCOLA (law, footnotes): see our OSCOLA referencing guide.
• IEEE (engineering, numeric): see our IEEE referencing guide.
• Vancouver (medical, numeric): see our Vancouver referencing guide.

In-text citation vs reference list: what is the difference?

The in-text citation is the brief marker inside your sentence – an author and year, or a number. The reference list (or bibliography) at the end gives the full details of every source. You always need both: the in-text marker points to the full entry.

Common citing mistakes to avoid

• Citing in the text but forgetting the matching reference (or vice versa).
• Mixing two referencing styles in one piece of work.
• Failing to cite paraphrased ideas, not just direct quotes.
• Copying a citation without checking it matches your style’s rules.

For wider help, see our guides on how to write an essay and how to write coursework, and the official APA Style guidance. For hands-on support, Projectsdeal offers an essay writing service and a dissertation editing service.

Frequently asked questions about citing sources

Do I need to cite paraphrased information?

Yes. You must cite paraphrased ideas as well as direct quotes, because the idea still came from another author even if the words are yours.

What happens if I do not cite sources?

Failing to cite sources is plagiarism, which can lead to lost marks, a capped grade or disciplinary action depending on your university’s rules.

Which referencing style should I use?

Use the style your department specifies in its handbook – commonly Harvard or APA in social sciences, OSCOLA in law, IEEE in engineering and Vancouver in medicine.

Can I use the same reference twice in one piece of work?

Yes. If you cite the same source more than once, each in-text citation follows the normal rules for that style (author-date for Harvard/APA, a footnote or numbered reference for OSCOLA/Vancouver/IEEE), but the source only needs to appear once on your final reference list or bibliography, with its full details.

Do I need to cite common knowledge?

No, information that is widely known and undisputed within your field, such as basic historical dates or well-established facts, generally does not need a citation. However, if you are unsure whether something counts as common knowledge in your discipline, it is safer to cite the source, since markers often penalise under-citation more heavily than over-citation.