What is database hint?

Excuse me, but could you please clarify what exactly a "database hint" is? I've come across this term in my research on optimizing SQL queries, but I'm still a bit hazy on the specifics. Is it a piece of code or a setting that can be used to guide the database engine in how it should execute a query? Are there different types of hints, and if so, what are some examples? Also, are there any potential drawbacks or risks associated with using database hints, and if so, how can they be mitigated? Thank you for your help in clarifying this topic.