"Arms and eyes upraised toward the sun and a prayer on his lips, an elf begins to glow with an inner light that spills out to heal his battle-worn companions.

Chanting a song of glory, a dwarf swings his axe in wide swaths to cut through the ranks of orcs arrayed against him, shouting praise to the gods with every foe’s fall.

Calling down a curse upon the forces of undeath, a human lifts her holy symbol as light pours from it to drive back the zombies crowding in on her companions.

Clerics are intermediaries between the mortal world and the distant planes of the gods. As varied as the gods they serve, clerics strive to embody the handiwork of their deities. No ordinary priest, a cleric is imbued with divine magic." - Player's Handbook

A devoted priest to their cause, clerics are the magical support of any party, having a large access to healing magics. Depending on the cleric in question's domain, they could have a large variety of spells, beliefs, and specialties. And with the large variety of gods in the D&D universes clerics have a large variety of deities to worship, and with the D.M.'s help you can even add a new one to worship. The natural enemy of undead, in most cases, clerics have the ability to channel the divine energies of their deity, creating different effects depending on their domain. Role-playing wise clerics have a strict code they follow to based upon the will of their deity they must follow to keep their god's good will, but that code depends on the domain, god, and player/D.M. collabertation. Overall this class is good for a player who wants to support others and keep them alive longer in dangerous battles, while calling down divine judgement on their enemies.