fide master:
Introduced in 1978, FM ranks below the title of International Master but ahead of Candidate Master. The most usual way for a player to qualify for the FIDE Master title is by achieving an Elo rating of 2300 or more. The current title regulations can be found in the FIDE handbook.[2]
candidate master:
The most usual way for a player to qualify for the Candidate Master title is by achieving an Elo rating of 2200 or more. Candidate master ranks below other FIDE titles.
national master:
In the United States, the title of "National Master" is awarded for life, regardless of whether the rating of a National Master subsequently goes below 2200.[1] In August 2002, this position was codified (after being recognized as the existing status quo) by the USCF Policy Board with the passage of a motion stating "Any USCF member who has had a regular post tournament rating of 2200 or higher (published or not) has demonstrated a significant level of chess ability and is recognized by being automatically awarded the lifetime title of National Master."
What is the difference between FM (Fide Master), CM (Candidate Master) and NM (National Master)?
I know GM (Grandmaster) is the best and that requires 2500 rating to get as well as winning certain tournaments to get norms.
I also know IM (International Master) is the second best and requires 2400 rating as well as getting different sort of norms to get.
But what rating do FM, CM and NM require? Which is the easiest and which is the hardest to get? How do you acquire each of them?