Some players put rakeback in the "Yeah, whatever, I'll get around to checking that out someday" category but that can cost you thousands of dollars in cash over the long run.
Online poker sites make their money by taking a small percentage of every pot (usually .05 to $3, depending on the stakes) which is called the rake.
The rake is typically pretty small and at a maximum just 5-10% of the total pot; if you're playing low-stakes Texas Holdem and win a pot worth $1, the rake that is deducted is usually .05 or .10.
The same is true of online poker tournaments and Sit-n-Gos, with the rake being the extra fee you pay when you enter - e.g. a $24+$2 tournament or a $10+$1 Sit-n-Go.
The rake is so small that some players don't even really notice it, especially at cash games, but it can quickly add up into sizable amounts of money over tens of thousands of hands or tournaments.
Rakeback, then, is exactly what it sounds like: getting some of that rake back.
A player with a 30% rakeback deal from a site like RakeBrain will get back 30% of the rake he or she paid during the previous month, deposited directly to his or her online poker account.
While some other factors can impact how much rakeback you get, the general math is pretty simple: rake $100 with the above deal and you'd get $30 back; rake $1,000 and you'd get $300 back; rake $10,000 and you'd get $3,000 returned to you, etc.
Not every rakeback deal is the same, however, with different sites offering slightly more or less as far as the percentage you'll get back.
If you're wondering why a poker site would ever just give you something for nothing, it's not because they're generous and warm-hearted.
The online poker industry has become very competitive and sites will do anything to keep their customers, even if it means giving up a percentage of the rake for some players each and every month.
For many sites it's better to return 30% of your rake to you to keep you playing and happy (keeping the other 70% of what you rake) than to lose you to another site and lose your play entirely.
The actual process of getting rakeback is simple, assuming you don't already have an account with the site you'd like to get rakeback from.
Just check over the deals at RakeBrain for the best fit for you and sign up for the deals you like.
Once your account is confirmed and you get the green light, all you need to do is play poker.
Your rakeback for the previous month is usually added automatically to your poker account every month, but it can vary from site to site.
Check the terms and conditions where you sign up to be sure.