On this page I'll try to illustrate how toilets become plugged and the best way to go about clearing them. Just about every toilet on the planet, except out-houses and airplanes, have toilets that are similar to the one above. On this toilet the trap goes toward the rear.
Some models have the trap going up toward the front of the bowl before turning down to the drain.
For the purposes of this instruction, it doesn't matter which type you have. The normal water level in the toilet is that of the blue line. The water must be at this level for some important reasons. If the water were too low, a lot of the flush would go to filling the bowl before the actual contents began to flow toward the drain. If the water were lower than this, sewer gases would be able to come up through the fixture and into the room.