Apollo is a Greek god with many, and sometimes conflicting attributes. He is a patron of intellectual pursuits, the arts, and prophesy. He leads the Muses, for which reason he is called Apollo Musagetes. Modern philosophers and psychologists sometimes contrast Apollo with Dionysus, god of wine and frenzy. Apollo inspires seers with prophecy while Dionysus fills his followers with madness.
Apollo is sometimes called Apollo Smitheus, which may point to a connection between the god and mice, since Apollo shoots plague arrows to punish disrespectful humans. Note that while he may send disease, Apollo is also associated with healing and the father of the healing god Asclepius.
Over time Apollo came to be associated with the sun, taking over the role of the sun Titan Helios. You may see him with his sister Artemis, a virginal goddess of the hunt with her own set of contradictory attributes, but who, like Apollo, came to be identified with another of the celestial orbs; in her case, the moon, a function she took over for the moon Titan Selene. Their parents are Zeus and Leto.