A combination photo shows various popular street foods under $6 from various hawker food stalls and eateries in Singapore, taken between July 28 to 31, 2016. Top row (L to R) bak chor mee, soya sauce chicken; Middle row (L to R) laksa, hokkien mee, nasi lemak, ice kachang; Bottom row (L to R) rojak, roti prata and satay. (Photo by Edgar Su/Reuters)

Muhannad al-Kadiri (R),18, and Ibrahim Eid, 16, demonstrate their Parkour skills over a military vehicle in the rebel-held city of Inkhil, west of Deraa, Syria, February 4, 2017. (Photo by Alaa Al-Faqir/Reuters)

A boy holds the remains of a mortar shell which hit a residential building in the village of Staromikhailovka, outside the separatist-held city of Donetsk, Ukraine, May 24, 2016. (Photo by Alexander Ermochenko/Reuters)

Thoughts. They fly through the broad expenses of our mind, floating gracefully in midair, going into the clouds, and then reemerging once again. Some are quick and furtive, others are grand and majestic. We reflect upon them as they enter our minds, and once they leave, they are usually gone for good. However, some thoughts are different. These thoughts resemble a flock of angry birds or a swarm of hungry moths that invade your mind, slowly eating away at your sanity, strength, and desire to live. Such thoughts often plague that minds of people with Obsessive Compulsive disorder. They completely occupy their time; constantly there; ever-present. With his book sculpture, Thomas Wightman was able to accurately convey the way these thoughts consume the mind, slowly building a nest within it, resisting all attempts to drive them away.

Andrey Karr from Western Riders Slacklines at sunset above big waves in Nazare, Portugal on December 27, 2017. (Photo by Aidan Williams/National Geographic Travel Photographer of the Year Contest)

“Basunga”. Basunga (3 weeks-old newborn with albinism) is happily sleeping with his cousin. For now, he does not yet realize the difficulties he will face to integrate into the Congolese society as a PWA. The success of his integration will greatly depends of how he accepts himself and his skin condition a and how educated he will be. Photo location: Kinshasa, Congo RDC. (Photo and caption by Patricia Willocq/National Geographic Photo Contest)

An American soldier walks ahead of an MKIV (Mark IV) British-made tank, circa 1918. (Photo by Hulton Archive/Getty Images)

Iraqi women practice at the sports club in Diwaniya, Iraq on November 10, 2018. On the blue mats of the al-Rafideen Club in the conservative city of Diwaniya, some 180 km (110 miles) south of Baghdad, some 30 female wrestlers, some still wearing headscarves, train three times a week. When a big competition comes up, they train every day. (Photo by Alaa Al-Marjani/Reuters)