Quite self-explanatory, the toilet chain is a chain that connects the flushing handle to the flapper valve. By having this chain, the handle and flapper are able to work in sync to complete the full flush cycle. However, the chain can be a tricky piece within a toilet. The chain is very specific— if it is too tight or too loose, too short or too long, the entire interior toilet system will not function properly.
If the chain breaks, the entire toilet breaks essentially. Without the chain, the handle no longer works. Instead, you will have to manually flush the toilet, having to lift the lid each time to drain the tank into the bowl to complete the cycle. Thankfully, once you find the proper chain, the replacement process is quite easy! The chain works closest with the flush lever. However, it also works alongside the flapper, overflow tube, and refill tube.