Terms of Service (TOS)
The Terms of Service is set of rules an individual or organization must abide by in order to use a service. A Terms of Service agreement is legally binding (except in cases where the individual is below a certain age and does not have parental consent or the terms of service violates local, state, or federal laws) and generally covers various aspects of the user’s interaction with the service, such as how the user’s data will be used, how the user can use the service (e.g. you can send personal email but you can’t send commercial email), and so on.
Terms of Service agreements are widely criticised as being arcane and difficult to read; so much so that it is rare for end users to actually read them and to instead blindly accept the terms.