Sperm donation is done to help an individual or a couple conceive a baby. You might choose to make a sperm donation to help those who are unable to conceive — such as a woman who doesn't have a male partner or a couple experiencing male infertility.
If you donate semen to a sperm bank, you'll likely be paid for each donation that passes the sperm bank's screening process. Payment is intended to compensate you for your time and any related expenses. The amount is typically low enough so that money isn't the main incentive for donating.