What is Telegram and why was its CEO arrested in Paris?

Pavel Durov, the founder and CEO of the messaging app Telegram, was arrested in Paris over the weekend over allegations that his platform is being used for illicit activity including drug trafficking and the distribution of child sexual abuse images.

Durov, who was born in Russia, spent much of his childhood in Italy and is a citizen of France, Russia, the Caribbean island nation of St. Kitts and Nevis, and the United Arab Emirates. He was taken into custody at Paris-Le Bourget Airport in France on Saturday after arriving from Azerbaijan and released Wednesday after four days of questioning. He was ordered to pay 5 million euros for bail and directed to report to a police station twice a week, according to the Paris prosecutor’s office.

In a statement posted to its platform, Telegram said it abides by EU laws and its content moderation is “within industry standards and constantly improving.” Durov, the company added, “has nothing to hide and travels frequently in Europe.”

Here are some details on Telegram, the app at the center of Durov's arrest.