TTPs, or “tactics, techniques, and procedures,” are defined as the following:
The behavior of an actor. A tactic is the highest-level description of the behavior; techniques provide a more detailed description of the behavior in the context of a tactic; and procedures provide a lower-level, highly detailed description of the behavior in the context of a technique.
— NIST
In other words, TTPs provide a detailed picture of how an adversary would act in a computer system.
Refer to MITRE ATT&CK for an extensive list of TTPs.