To attract your business many casinos will add a bonus to your initial deposit, usually 10% but I have seen it go as high as 100%. When you accept a bonus you are usually required to meet a certain level of betting action to cash out the bonus. I have seen the total amount bet required range from three times the deposit (Pinnacle Sportsbook) to 40 times the sum of the deposit plus the bonus (Connecto Casino). Read the rules carefully before you start playing. After opening an account wait at least 15 minutes for any welcome e-mail to come in. Sometimes this e-mail will indicate different rules than what the web site says about earning a bonus. Assume that you have to meet the more stringent of the conditions. Regardless of what the rules are you should more than exceed them. If pressed for specifics I would say play at least 50% more than required but 100% or more is better. Some online casinos claim, and exercise, the right to deny bonuses to customers they feel are in it only for the bonus, as opposed to the enjoyment of the casino. Finally I would be suspicious of casinos that you have never opened an account with who send unsolicited bonus offers. I have created an automatically updating list of the best bonuses https://slotipedia.net/ in terms of wagering requirements and other terms for each of the popular casino games.