Why do railway tracks have gaps?
Short answer
Steel rails expand when they get hot and contract when they cool. On tracks made from shorter rail sections, small gaps at the joints leave room for that movement.
How it works
If a long steel rail became hotter while being forced to keep exactly the same length, the resulting forces could push the track sideways. A joint gap gives thermal expansion somewhere to go.
Many modern railways use long welded rails with fewer visible joints. They manage temperature and the forces in the rail so that the track remains stable without relying on regular visible gaps.
Key point
The gaps are not there to make trains ride roughly. They are one way to handle the expansion and contraction of steel safely, and the visible design depends on the track system.