In Depth: Syrian Conflict and Hillary's position
Some of the following is based on my conversation with an Arabic interpreter with the United Nations. He really helped me better understand the challenges, and I hope I did a good job remembering and relaying what I learned.
Haffez al-Assad, the father of the current leader Bashar al-Assad, was self described as non-religious, but under his reign commissioned over 1000 mosques to be built. Through people's religion he was able to control them, as the leaders of the mosques also became informers to the government. When people were critical of the regime, they would be informed on by the religious leaders, and they would disappear. Life became more and more difficult over time. For example, just to start a business you had to give a member of the Assad family 50% ownership in the company while you do all the work. The Assad family comes from a minority group called the Alawites, who control what is known as the Ba'athist party.
While there are some small groups of Kurds in Syria, there are no major cities that are majority Kurd like Iraq. So leveraging the Kurds to help defeat the Assad regime would be limited at best. Complicating matters is the ongoing conflict between Turkey and the Kurds that have a long history of territorial disputes, etc. Further complicating matters is their are Kurdish groups that are also sympathetic to Russia, and both the US and Russia have supplied them with arms.
Aleppo used to be a city of about 5 million and over 3 million have fled. The Western part is still mostly intact, and there are more people sympathetic to Assad in this region. That being said, there are many that are not but simply keep their mouths shut. Aleppo is a very fertile region and known for Agriculture (something like California).
When Obama figuratively drew the line in the sand about using chemical weapons in Syria, they crossed it, but Russia in a shrewd diplomatic move said they would work with Assad to remove the chemical weapons (and the probably did this). But the problem is they saw this as an opportunity and switched to arming Syria with very powerful and destructive weapons like barrel bombs that are non-chemical. And of course they are bombing places mostly around Aleppo almost daily. Russia has maintained a naval base in Syria for a long time, and it is very strategic to have this warm water port.
Turkey, a (now somewhat shaky) member of Nato moved into Northern Syria above Aleppo soon after the coup attempt on Erdogen. Because the possible leader of the coupe lives in the United States, this has led to tension between the US and Turkey. However, the US still has bases in Turkey, and also good is that Russia would not likely attack the territory in Syria that Turkey controls with troops and artillery.
Worth noting is Iran is a close ally of the Assad regime also and send weapons other reinforcement. Iraq was once controlled by Saddam Hussein, a Sunni Muslim. The Sunnis in Iraq are a minority, while the Shia are a majority. Iraq is a Shia Muslim country. The Free Syrian Army (FSA) which is fighting against Assad are 90% Sunni. When Bush disbanded the Iraqi Army, many joined up with Al-Queda, and then later ISIS. You may have read some reports about weapons supplied by the US getting to ISIS in the past, and usually the connection discussed is the FSA, but they are also the people of Aleppo and the largest group against Assad. Aleppo was long a peaceful place like California. 
When it comes to ISIS, pretty much everybody hates them in Syria. It is mostly composed of foreigners, and ISIS has been subdued substantially. They are still a problem in some of the more rural, less populated area, but they are not nearly as much a force to reckoned with now.
The more serious threat may very well be Russia continuing to bomb people and supporting the oppressive Assad regime and Iran. Going back to Iraq, since Iran is Shia, and a majority of the Iraqi people are Shia, Iran is now sending in people into Iraq and starting to control the politics of Iraq more than ever before.
I would like to think that after reading this one would not form the opinion that any of this is simple. It is through a better understanding of the forces at work that we can improve our strategy. The establishment of a no-fly zone has been suggested, and of course Hillary Clinton has suggested we need to do this. By increasing the number of areas that people can live somewhat peacefully (as Turkey has tried to do in Northern Syria), maybe there is hope that some stability can return. But any sort of sympathy toward Russia as Trump has suggested, or thinking just bombing Isis or Iran solves everything, seems incredibly distant from reality.
