A lawsuit is a legal claim brought before a court by one party against another to seek a remedy, usually for breach of a legal right or duty. In UK and Irish practice, more precise terms such as “claim”, “action” or “proceedings” are commonly used, but “lawsuit” is widely understood as a descriptive, non‑technical expression rather than a defined statutory term.In England and Wales and Northern Ireland, a lawsuit typically refers to civil court proceedings commenced by a claim form, writ or originating application, seeking remedies such as damages, injunctions, declarations or specific performance. In Scotland, the equivalent concepts are an “action” (e.g. an ordinary action or summary cause) or “proceedings” raised in the sheriff court or Court of Session. In Ireland, “proceedings” or “action” are the usual terms, commenced by originating summons, plenary summons or civil bill.The term covers all stages of the civil litigation process, from issue and service through pleadings, disclosure, interim applications, trial, judgment and enforcement, and may include appeals. It does not ordinarily include criminal prosecutions, although non‑lawyers may use it loosely in that sense.