A newcomer wants to help an open project but cannot tell whether it needs translations, bug reports, new features, or nothing at all. Contribution guidelines turn that uncertainty into a path: what help is welcome, where to begin, and what happens after work is submitted.
Contribution instructions make a project's invitation to help actionable. They are different from a license, which grants permissions, and a code of conduct, which sets expectations for behavior. A contribution guide explains the practical route into the work.
A community map could show how to submit a corrected location, what evidence to include, and who reviews changes. Examples are especially useful when experienced members no longer notice how much background knowledge they assume.
A guide can become another obstacle if it is enormous, outdated, or written as a list of mistakes newcomers must never make. It should also set realistic expectations: a volunteer maintainer may not be able to review every proposal immediately. The aim is to make participation more predictable on both sides, giving contributors enough information to avoid wasted effort and maintainers a consistent explanation they do not have to repeat individually.