So, Erin Palette asked why the Autobots and Decepticons are at war with one another. It's a good question, and I'd like to say that there's a single coherent explanation for it. Sadly, given the sheer number of different Transformers continuities there are, it's hard to find a consistent answer to anything.
So I'll do my best to answer the question from the perspective of the original cartoon series. I thought about tackling it from the Dreamwave comic series as well, but I'm a lot less confident with my knowledge of that stuff right now, and I don't have the issues nearby for reference.
The origin of the Transformers in the original cartoon was somewhat fuzzy; we know that the Quintessons (five-faced robotic villain-types) were somehow involved, but the series wasn't exactly the greatest at keeping its continuity straight. There's some evidence to suggest that the Quintessons built the Cybertronians for specific purposes and sold them to other worlds for use as slaves, but a lot of that is speculation. It's specifically said, however, that the Autobots are built for science and research activities, while Decepticons are built for combat. The two factions come into conflict repeatedly, but eventually there comes the Golden Age of Cybertron, a long era of lasting peace.
The episode that gives us the best insight into this is "War Dawn," where the Aerialbots accidentally travel back in time, where they befriend a young Autobot by the name of Orion Pax. Orion's a good kid with a lot of ambition, and he really admires an up-and-coming revolutionary by the name of Megatron. Megatron's the leader of a new sort of Transformer, equipped with personal anti-gravity devices and outfitted with high-powered weaponry. Megatron is amassing followers, and Orion is keen on joining until the rebel betrays him. Thanks to quick action by Alpha Trion, one of the oldest Cybertronians, Orion Pax is rebuilt--into Optimus Prime. Prime goes on to amass his own army, and the war between the scientists and the soldiers begins once more (albeit seemingly more organized this time around).
The Wisdom/War dichotomy is central to the Autobot/Decepticon conflict. The Autobots seek progress and betterment through the quest for knowledge; the Decepticons seek progress through increasing power and subjugation of others. It's telling that one of Megatron's earliest acts in building his army was to create a device that would permanently reprogram Cybertronians to be loyal to him. Similarly telling is the fact that the Autobots' greatest weapon is an artifact containing the combined power and wisdom of every one of the Autobots' many leaders.
So the Decepticons want power, and will do anything to get it. On Earth, that means elaborate plans to dominate the planet and turn their resources into Energon Cubes. The Autobots seek knowledge and prize freedom, and see it as their responsibility to protect others from the menace of the Decepticons.