A toilet flange is a pipe fitting that connects a toilet unit to the drain pipe that is on the toilet floor.​

A wax ring tightly seals the flange to the bottom of the toilet. This keeps the flange bolted to the toilet rather than the bathroom floor. Without the flange, the toilet will not sit securely in line with the drain pipe. In theory, the toilet could be bolted to the floor without the flange but over time the toilet will leak. You’ll want to install a flange when you install a toilet to avoid leaks In other words, a toilet flange is absolutely essential.