system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the key differences between Al-Qaeda, Islamic State, the Taliban, and whatever other factions there are over in the middle east?

And why do the hate each other so much?
gpt
1. Al Qaeda- a stateless organization formed during the 1990's by Osama bin Laden. Al Qaeda's main goal was to abolish the modern national borders and governments and establish a "Caliphate", or a single, large country based on Sunni Islamic law. Bin Laden believed that by launching terrorist attacks against the West and Western-allied governments in the Muslim world, the world's Sunni Muslims would be inspired to rise up, overthrow their secular governments, and build the Caliphate. The Al Qaeda organization was structured very loosely, so killing or capturing certain leaders didn't hugely impact the organization as a whole. Over time, "Al Qaeda" became more of a brand or franchise than an actual organization, something senior Al Qaeda leaders encouraged.

2. The Islamic State is a large, hybrid Sunni Islamic militant group that operates a Caliphate in large parts of Syria and Iraq. IS actually began as a branch of Al Qaeda in the late 1990's and rose to prominence during the US war in Iraq. During this time, it was known as Al Qaeda in Iraq and Islamic State of Iraq. When the Americans and Iraqis finally stamped out most of the insurgency in 2008-2009, AQI seemed to be out of steam. However, the Syrian civil war, which began in 2011, breathed new life into AQI/IQI and it quickly became one of the most prominent groups fighting the Assad regime. This new cause celebre, as well as a growing influx of foreign recruits, let them renew their fight against the Iraqi government as well as against the Syrian government. During this time, the group labeled itself ISIS (Islamic State of Iraq and Syria) and formally split from Al Qaeda. Although AQ and ISIS share a common general philosophy, AQ believed in being patient and letting the Caliphate come about on its own whereas ISIS wanted to establish the Caliphate with their own hands as soon as possible. In the summer of 2014, ISIS went on a blitz throughout large parts of Iraq and Syria, gaining an enormous swath of territory and officially declaring this territory as the new Islamic Caliphate. They changed their name to the Islamic State to reinforce their global ambitions rather than just regional ones. IS is a hybrid organization. Whereas Al Qaeda has no military units and few actual headquarters, IS has a de-facto state complete with its own government and semi-organized military. However, IS also has continued Al Qaeda's strategy of encouraging others to take up the IS "brand" and carry out their own attacks, while still threatening the West with attacks on its soil. So, in effect, it combined Al Qaeda's do-it-yourself, media-focused terrorism model with more traditional nation-building strategies. They aren't enemies of Al Qaeda in the true sense, but nor have they shown an interest in reconciling with their parent group either and they maintain a rivalry in terms of attracting recruits and media attention.

3. The Taliban is a Sunni Islamist militant group operating in Afghanistan and Pakistan. Whereas Al Qaeda and IS have traditionally been dominated by Sunni Arab Muslims, the Taliban are all Sunni Pashtun Afghans. They ran their own Caliphate in Afghanistan from 1996 until the US knocked them from power in 2001. They share many common beliefs with AQ and IS (even sheltering AQ during the 1990's, and thus invoking America's wrath after 9/11), however, they are focused on local goals, primarily regaining control of Afghanistan. They have no love for the West but have shown no efforts to conduct attacks outside of the Afghan/Pakistan region. 

Now, those three factions above are all Sunni Muslim jihadists. The Assad government in Syria and the Iranian government are Shiia, also called Shiites. Assad's regime is secular but run mostly by Shiia, whereas Iran is a Shiia theocracy. (The Sunni/Shiite divide is roughly analogous to the Catholic/Protestant differences in Christianity.) Iran supports Assad because Assad has been a loyal ally and is the only Shiite-dominated government in the Arab world (the Iranians are Persians, not Arabs.) Also, Assad's government acts as Iran's footprint on the other half of the Middle East, helping them pursue Iranian agendas in Lebanon and the Palestinian territories. Iran does *not* want to lose their Syrian ally. Within Iraq, the Shiites control most of the Iraqi government. But ~40% of the Iraqi population is Sunni, which has created widespread mistrust of the American-backed Iraqi government in the Sunni provinces.

You've also got the Kurds, who live in Syria and northern Iraq. The Kurds aren't Arabs- they're Kurds- but they are also Sunni Muslims. The Kurds have always been very pro-American and have been doing the majority of the ground fighting against IS. However, the Kurds have a very long and very deep antagonism with the Turkish government. Turkey doesn't like IS, but they also don't want to help the Kurds do much of anything. There are still also millions of Christians in the region but they have been fleeing in increasing numbers for years for reasons that shouldn't need much explaining.

There are other, smaller factions in play with all this but this is a good general explanation of what's going on and why there are no easy solutions at hand.