Transformers is the well-known franchise that follows the interstellar war between the noble Autobots and ruthless Decepticons, two factions of sentient humanoid machines locked in an eons-old civil war that began on their homeworld of Cybertron and brought them to Earth, catching Humanity in the crossfire. These machines have the amazing capability to assume other forms, generally Earth vehicles, to remain on the planet incognito as robots in disguise - which earns them their nickname as Transformers. This particular theme is usually referred to as the Aligned continuity and is the timeline that concerns itself with the events of the games War for Cybertron and Fall of Cybertron, the novel Exodus along with the Transformers: Prime television series. Something of a chimera of every piece of Transformers literature created, Aligned seems to be set on creating a 'definitive' Transformers universe and yet in no way supercedes the others. The setting falls somewhere between the original G1 series and Michael Bay's films in tone and appearance.
The flagship of the Aligned continuity is the Transformers: Prime TV series. The series follows Optimus Prime and his Autobots - Arcee, Ratchet, Bulkhead and Bumbleebee - as they, along with their human partners, protect Earth against Megatron and his Decepticons. This is the continuity where Soundwave is silent, Earth is home to Unicron, Cybertron is a barren wasteland, Megatron is infused with Dark Energon and Wheeljack is an adept swordsman. Interestingly, despite their attempt to make it 'definitive', there are several contradictions between the novels, games and tv series - for the ease of everyone involved, it would be best to explain these discrepancies as just the result of such a long and brutal war.