(CNN)If necessity is the mother of invention, no one knows it better than the estimated 200,000 to 300,000 Syrians living under siege in eastern Aleppo. For more than four years, they have been caught in a deadly conflict between rebels fighting President Bashar al-Assad's government, backed by its ally Russia. With ISIS in the surrounding countryside, they have no where to run and everything to lose.
Aleppo: Enduring and innovating in the midst of conflict
The residents of eastern Aleppo have endured daily firefights, missile strikes, barrel bombs and even allegations of chemical attacks. As a result, many of their homes and and much of the city's infrastructure have been destroyed. To make matters worse, a government blockade has prevented food, fuel, medicine and other supplies from entering the city.
In August, the last remaining doctors in the war-torn city wrote an open letter to President Barack Obama pleading for help.
"We do not need tears or sympathy or even prayers," the doctors said. "We need action."
Without an immediate halt to the violence, human rights organizations warn of a humanitarian disaster, including the threat of mass starvation.
Under these conditions, Syrians have been forced to find new and innovative ways to survive. CNN has compiled a collection of powerful images showcasing their ingenuity in the face of continued hardship.
With little access to electricity or clean water, simple tasks like cooking can be an obstacle in Aleppo. Resident Khaled Kurdiyah uses a metal container that he outfitted with a fan that creates a highly controlled bonfire to replace rare gas-fired stoves. The mechanism also uses minimal firewood, which has become scarce in the besieged city. He uses the contraption to boil water, cook and generate heat.
Abu Ahmed, left, and Abu Majd prepare a barrel filled with plastic as part of a refining process they've developed to produce fuel, which has become rare and expensive.
Abu Ahmed says he fills a metal container with scrap plastic and heats it until everything melts into liquid. He continues to boil the liquid until it turns to steam. That steam is passed through tubes that run through cold water. Once cooled, the steam turns back into a liquid fuel that can be used for a range of daily needs. He says he can even create gasoline, depending on what types of plastics he melts.
Abu Rahmo, a mechanic by trade, has invented a unique way to power car batteries. By welding a small generator to the back of an old bicycle, he's able to charge the battery simply by peddling. Once charged, the battery's electrical currents can be used to power everything from light bulbs to vehicles.
Amir Sendeh tends to plants in his small rooftop garden in the Kalasseh district of Aleppo. With the government blocking food from entering the city, Syrians have been forced to start growing their own crops, which they eat and trade for goods. Among the most popular crops are tomatoes, mint and even tobacco.
Syrian ingenuity is not just limited to adults. Their children, with seemingly unbreakable optimism, have found creative ways to play amid the violence and destruction. These Syrian boys transformed a bomb crater in the Sheikh Saeedn eighborhood of Aleppo into an inground swimming pool.
Since 2011, when the Syrian civil war began, nearly 500,000 people have been killed and millions more injured and displaced.