The Syrian Civil War began in 2011. Since then, more than 450,000 Syrians have been killed and more than a million injured. More than half of the country's pre-war population has been displaced from their homes.
Early in 2011, revolts brought down both the Tunisian and Egyptian presidents. This became known as the "Arab Spring."
In March 2011, peaceful protests erupted in Syria as well, after 15 boys were arrested and tortured for writing graffiti in support of the Arab Spring. One of the boys was killed after being brutally tortured. His name was Hamza al-Khateeb and he was 13 years old.
The Syrian government, led by President Bashar al-Assad, responded to the protests violently. It killed hundreds of demonstrators and imprisoned many more. In July 2011, a rebel group called the Free Syrian Army formed. Its aim was to overthrow the government. From there, Syria began to slide into civil war.
What caused the uprising?
Initially, lack of freedoms and economic troubles fueled resentment toward the Syrian government. The harsh crackdown on protesters increased public anger. Successful uprisings in nearby Tunisia and Egypt gave hope to pro-democracy activists in Syria.
Many Islamist movements were also strongly opposed to the Assad family’s rule. Though the term "Islamist" has come to be associated with violent groups, not all Islamist movements are violent. It is a broad term that refers to political activism based on the Islam, one of the world's major religions. There are Islamist groups that are violent and carry out acts of terror. The Islamic State (also known as ISIS or ISIL) is one of these groups. But not all Islamist groups are violent. A lot of them are peaceful. Many believe strongly in democratic ideas like freedom of assembly and a free press.
In 1982, Hafez al-Assad, the father of the current president Bashar al-Assad, ordered a military crackdown on an Islamist organization called the Muslim Brotherhood. The operation he ordered killed between 10,000-40,000 people.
Climate is also considered to have played a role in sparking the 2011 uprising. Syria experienced a severe drought from 2007 to 2010. This made it difficult for farmers to make a living. It caused as many as 1.5 million people to migrate from the countryside into cities, which exacerbated poverty and social unrest.
Just as there are different types of Christianity, like Catholicism and Protestantism, there are different types of Islam. Sunni is the largest branch, and Shiites make up a large minority. The Sunni-Shiite divide dates back centuries, as do the tensions between them. Although most Syrians are Sunni Muslims, Syria's government, including the Assad family, has long been dominated by members of another group, the Alawites. The Alawites broke off from the Shiite branch over 1,000 years ago. Today in Syria, most groups fighting against Assad's government are Sunni Muslims. Minority religious groups, like the Alawites and Shiites, tend to support the Assad government.
These divides are reflected throughout the region. The majority-Shiite countries Iran and Iraq support Assad. Meanwhile, Sunni-majority countries, including Turkey, Qatar and Saudi Arabia staunchly support the rebels.
The role of foreign involvement
Foreign influence has played a large role in Syria's civil war. The United States has led international coalition that has bombed Islamic State targets since 2014.
The Islamic State is an extremist group. It emerged in 2013 in northern and eastern Syria after overrunning large portions of Iraq. The group quickly gained international notice for its brutal executions and its use of social media. It has attacked both government and opposition forces. Its goal is to create its own Islamic state across Iraq, Syria and beyond.
Russia has also gotten directly involved. In September 2015, it started bombing what it referred to as "terrorist groups" in Syria. This included ISIL, but also rebel groups backed by western states.
Russia has also deployed military advisers to help Assad. Several Arab states, along with Turkey, have provided weapons and materiel to rebel groups in Syria.
Many of those fighting come from outside Syria – the ranks of Islamic State fighters include a sizable number of people from around the world.
Although the United States has stated its opposition to the Assad government, it has hesitated to involve itself deeply in the conflict. This was even after the Assad government crossed what President Obama had called a "red line" – using chemical weapons.
In October 2015, the U.S. scrapped its controversial program to train Syrian rebels. It was revealed that it had spent $500 million but only trained 60 fighters.
The situation today
On November 26, the Syrian army launched an attack on a city named Aleppo. On December 13, the Syrian army claimed that 98 percent of east Aleppo was in the hands of the Syrian government.
Besides Aleppo, the Syrian government currently controls the capital, Damascus. It also controls parts of southern Syria, much of the area near the Syrian-Lebanese border, and the northwestern coastal region. Rebel groups, the Islamic State and Kurdish forces control the rest of the country. Kurds are an ethnic group primarily centered in Iraq, Iran, Syria and Turkey. Most, but not all Kurdish people are also Sunni Muslims.
Rebel groups frequently fight each other. The Free Syrian Army has weakened as the war has progressed, while extremist groups became empowered.
Meanwhile, Kurdish groups in northern Syria are seeking self-rule, which has alarmed Turkey's government. It fears its large native Kurdish population may demand greater autonomy as a result.
On August 24, 2016, Turkish troops backed by the Free Syrian Army, launched an operation called "Euphrates Shield." Its goal was to liberate the Syrian city of Jarablus from Islamic State fighters. This operation is considered to be the first Turkish ground intervention in Syria.
Effects beyond Syria's borders
The Syrian war is creating deep effects far beyond the country's borders. Lebanon, Turkey and Jordan are now housing large and growing numbers of Syrian refugees. This is also impacting European countries.
Fighting has occasionally spilled over from Syria into Lebanon, contributing to the country's political polarization. Several rounds of peace talks have failed to stop the fighting.
With much of the country in ruins, millions of refugees abroad, and a population deeply traumatized by war, one thing is certain. Rebuilding Syria after the war ends will be a lengthy, extremely difficult process.