When you're being selfless, you're thinking of other people before yourself. Selfless is the opposite of selfish.
If you're selfless, you think less about your self, and more about others — you're generous and kind. Being selfless is similar to being altruistic — another word for giving to others without looking for personal gain. If you give time, money, or things to other people without expecting something in return, that's selfless. Most people would agree that the world would be a better place if there were more selfless behavior.