MITRE is a non profit company that works for the common good in the areas of cybersecurity
MITRE was the first to address the need to track and catalog the TTPs employed by APT orgs/groups against business Windows networks in 2013. FMX (Fort Made eXperiment), an internal experiment was where it all began
has a bunch of matrices that provide us with systematic and structured flows of the TTPs in various feilds of cybersec such as the ATT&CK and D3FEND matrices and a bunch of others
we mainly refer to the enterprise matrix when we talk about the MITRE ATT&CK Framework
ATT&CK is an abbreviation of Adversarial Tactics, Techniques & Common Knowledge
the first row items are the various tactics and the columns are the techniques used for that specific tactic. the techniques with gray bars have nested sub tactics within them
each TTP listed has everything from which groups use it, how its used, how to mitigate it etc etc
