Data provenance has evolved from a niche topic to a mainstream area of research in databases and other research communities. This article gives a comprehensive introduction to data provenance. The main focus is on provenance in the context of databases. However, it will be insightful to also consider connections to related research in programming languages, software engineering, semantic web, formal logic, and other communities. The target audience are researchers and practitioners that want to gain a solid understanding of data provenance and the state-of-the-art in this research area. The article only assumes that the reader has a basic understanding of database concepts, but not necessarily any prior exposure to provenance.