Editorial standards

Last updated 22 October 2026.

Primary sources only

Articles are written from primary sources: the peer-reviewed paper (cited by DOI), its open-access full text or preprint, and records published by official bodies such as space agencies, national institutes and clinical-trial registries. News stories, videos and other blogs may tell us what people are curious about, but they are never used as the source of a fact, and their text and images are not reproduced.

A source for every number

Every figure in an article, such as a measurement, date, dose or percentage, can be traced to a source in the article's Sources list. Where we convert a unit or round a number, the article says so. Each article shows the date its sources were last checked.

Stage and limits

Each article says how far the work has come (for example, a model, an animal study, a single observation or a replicated result) and repeats the limits the researchers themselves state. When scientists disagree, we describe each position and cite it.

What we do not do

• No sensational headlines. Titles are the question the article answers.
• No medical, financial or engineering advice. Health articles report research results and stages only, and do not recommend or endorse any treatment.
• No details we could not confirm from a primary record; if a key detail could not be checked, the article says so.
• No images copied from videos or other sites. Diagrams are drawn for this site; any third-party image is public domain or openly licensed and credited.

Corrections

If an article contains an error, we correct it in the text, update the 'sources checked' date and note what changed at the end of the article. Report errors through the contact page, ideally with the source that shows the correct information.