A toilet that splashes too much when flushing is an irritating problem. Nobody wants to sit on or have to continuously clean up water that keeps splashing out of the toilet. Several factors can cause toilet backsplash. You can typically resolve these problems on your own.
Check to see if the water level in the basin is too high. Try lowering the water level by lowering the float arm if you have a diaphragm style ball cock. Turn the adjustment screw counterclockwise to lower the water level if your toilet has a floatless ball cock. Pinch the spring clip, and slide the float cup down to lower the water level if your toilet has a floating-cup ball cock. If your toilet has a an older plunger-valve style ball cock, replacing it with a diaphragm style ball cock will update and improve your toilet's valve system.
Make sure the bowl refill tube is properly inserted into the overflow tube. Toilets will often splash if this trap is not sufficiently refilled after flushing.
Check to see if the fill valve is cracked. Replace the fill valve if so.
Watch the flapper valve during a flush. It should stay up until almost all of the water is gone from the tank. If it drops too fast, install a new flapper.
Minimise the flow of water by installing a timed flapper. Set it to the shortest flush time.