On the web, a citation is usually a link plus a short phrase that says what the source is. Done well, it adds trust without slowing the reader down.

When a citation is needed

Cite any claim a reader might doubt or want to verify: statistics, dates, technical limits, rules, quotes and findings from studies. Common knowledge, such as the fact that HTML is used for web pages, needs no link.

Choose the best source. Prefer the origin: the official documentation, the law, the paper, the company statement. A news article about a study is second-hand. If you must use a secondary source, say so.

Make the link descriptive

Write "Google's documentation on robots.txt" and link that phrase, instead of "source" or "here". The reader should know what they will find.

Quote with care. Quote only what you need, keep the wording exact and mark it clearly. Otherwise paraphrase in your own words. Paraphrasing without credit is still taking someone's ideas.

Add the context

Mention the date or version when the source may change over time, for example "According to the Google Search Central documentation, as checked in September 2026".

Handle disappearing pages. Check links before publishing and again during updates. For critical sources, note the title and publisher so you can find a replacement.

Examples of good citation wording

  • "Google's documentation says that noindex requires the page to be crawlable." Link the phrase to the official page.
  • "The WCAG 2.2 guidelines set a minimum text contrast of 4.5 to 1." Link to the W3C page.
  • "According to OWASP's password storage guidance, Argon2id is the preferred choice." Link to the cheat sheet.

Each names who said it, says what they said and points to it.

Keeping a source list while you write

Paste links into a notes file as you research, with a line about what each one supports. When you draft, you can cite accurately without searching again. At the end, delete sources you did not use and double-check that quoted words match the original. A tidy list also speeds up later updates.

Citations and images

Images, charts and quotes need credit too. Use your own screenshots when you can, and say where an outside image came from. Check the licence before reusing it. If you cannot confirm that you may use it, replace it with your own.

Do not fabricate. Never cite a source you have not opened. If you remember a statistic but cannot find where it came from, leave it out.