I would presume that you are talking about War chariots in general. One of the more well known countries that uses chariots effectively was the ancient Egyptians.

Firstly, chariots not really used as a transport tool as just having warriors to ride on horses would be more efficient as chariots tend to be a little cumbersome. Chariots were used as a better platform for mobile archers as during that time period, saddles and stirrups were not invented then, so it was hard for an archer to shoot while controlling a horse, unless you are a Parthian, so chariots provided a relatively stable platform for a partially protected archer unencumbered by the need to steer.

Secondly, chariots as compared to archers on the ground are able to exploit the opponents' weak spot as they are high mobile, and during that time period, body armor was not so advanced yet. Due to their high mobility, they are also effectively used in chasing routing units by spearing them.

Those are the light chariots. As for the heavier chariots(the one with four horses), up to four men stood on a chariot, wielding polearms and close combat weapons. Javelins and bows were employed for range fighting. This chariot was a heavy construction and moved relatively slowly. Light infantry could keep up with them. The momentum of this heavy chariot was sufficient to break through enemy formations, causing an effect similar to heavy cavalry with lances. From popular fiction such as movies, it is depicted that the chariots are equipped with blades, however this is mostly untrue. Some generals, such as Cyrus II and Darius III of Persia and Mithridates of Pontus attached scythes to their chariot forces' wheels, in the further hope of breaking up enemy formations. Historically, however, this tactic had at best mixed success, either because the horses would not charge directly into closely packed formations or because the opposing force would simply stand far enough apart from each other to avoid the scythes and then pull out the drivers as they rode through the gaps created.

If you want to see the tactics on how they made used of the chariots, I would recommend reading up on the battle of Kadesh(1294 BC) which was one of the biggest battes between two of the superpower then with both sides using thousands of chariots.

So in conclusion, there is a difference between the two horse chariots and the four horse chariots. One carry archers, the other, warriors. The heavy chariots were used for shock actions, to break up formations so that the troops on the ground can take advantage of the disorder. The most common chariots is still the hit and run archer chariots. The chariots are never used for transporting warriors, unless it is the personal chariot of the war leader or a Noble. Hopefully this could answer your questions.

Where and when? Chariots were used all across in Eurasia for centuries.