Definition of bankroll
The bankroll of a poker player is the money he spends on the poker. What is meant by bankroll is like a bank account, but specifically reserved for poker. Depending on the seriousness of the gambler, his or her bankroll will vary. If you are a beginner player and want to get into the world of online poker, maybe you will deposit 100 euros in an online gambling room. If you make your bankroll grow, great, if not, maybe you'll retire. Your 100 euros will be what we call your bankroll.
Managing the bankroll
The management of the bankroll is a very important aspect for all poker players. Your bankroll will determine the limits you will be able to play (as well as your skills). With a bankroll of 100 euros, probably tables of cash game to 5 euros of buy-in would be appropriate for you. If you are highly skilled, perhaps a more aggressive management of your bankroll might be possible, but be aware that there is still the risk of losing your bankroll completely. If depositing for you and dipping into "your regular money" to invest in your "bankroll of poker" is not a problem, it might be worth considering. For tournaments, it is suggested to invest a maximum of 1% of your bankroll in each tournament played.