Some parents aren't married. They chose to live together without getting married. In legal terms, they are called “common-law” couples.
When common-law parents stop living together, they don't have to get a divorce because there is no marriage to end. But they do need to decide what will happen to their kids and how they will divide their property.
The laws on custody and visiting rights are the same for married couples as they are for common-law couples. Parents need to decide on living arrangements for the kids and on visiting rights, so that both parents have a chance to spend time with the kids. If common-law couples can’t agree, they have to go to court to ask a judge to decide.