ELO is the most popular rating system which is used to calculate chess strength of players in FIDE, USCF and the majority of chess federations and online chess websites (like ICC or Yahoo! chess). The higher ELO rating is the stronger a player is. In ELO system, a player moves from one class to another (say from class C to class B) for every 200 points earned. If the difference between ELO ratings of two players is 200 points, the strongest player will win about 75% of games. If the difference between ratings is 400 points, the stronger player will win about 95% of games. If the difference is 600 points the stronger side will most likely win 99.999% of all games. Let's say somebody with 1400 ELO plays somebody with 2000 ELO. The second one will win all games. Well, except for those drawn in case of tornado or fire…

Here is the list of titles with approximate ELO ratings:

• >2,700 - Grandmaster qualifying for the world championship match
• 2,500-2,700 - Grandmaster (GM)
• 2,400-2,499 - International Master (IM) or Senior Master
• 2,200-2,399 - National Master (NM)
• 2,000-2,199 - Expert or Candidate Master
• 1,800-1,999 - Class A
• 1,600-1,799 - Class B
• 1,400-1,599 - Class C
• 1,200-1,399 - Strong Beginner
• 1,000-1,199 - Beginner
• <1,000 - New player
• 100 - Minimal possible ELO rating