Castle Wiki

Certain category tags have been appended to episodes which share particular qualities or essential subject matter.

Thus far these include:-

Coffee - These are episodes in which an indicative and key role in the Caskett relationship is played out with the beverage.

3 little letters - Episodes with a large component of FBI, CIA, NSA, DHS, DEA, MIB or similar involvement.

(Chrazriit: I suggest using Feds instead; more descriptive)

OCG - Episodes in which a pivotal role is played by organized crime or street gangs.

(Chrazriit: I suggest organized crime, again more descriptive.)

Beckett Conspiracy - Those episodes which provide crucial information in the murder of Johanna Beckett, or the shooting of Kate Beckett.