What does it mean to create graffiti? What exactly is (or are) graffiti? Graffiti and street art differ, right? Almost everyone has an opinion on what constitutes (modern) graffiti. Consequently, the term has taken on the most varied meanings in the conversations of academics, in media coverage, or in daily life. So how can one be sure about the meaning of the term (or any graffiti-related term, for that matter)? This is why glossaries, dictionaries, and other types of lists with definitions exist on websites, at the beginning or end of coffee-table books, and in scientific articles. However, there is currently no generally available, updateable, broadly accepted and easy-to-expand list of graffiti-related terms. Therefore, in order to meet the need for systematisation and consistency required for a more comprehensive study of graffiti, project INDIGO embarked on the journey to create a graffiti thesaurus. Being a finite set of terms (i.e. a controlled vocabulary) with hierarchical relations, this thesaurus will make INDIGO’s graffiti classification explicit and hopes to serve as a reference for the broader (academic) graffiti community.