Hong Kong Protests: How does messaging app Telegram work and why is it so popular?

Telegram is a cloud-based messaging app that allows messages to be encrypted. It became one of Hong Kong's most downloaded apps during the anti-extradition bill protests.

Many protestors form groups to provide updates, exchange details on how and where to protest, as well as to request additional supplies. Some chat groups even have tens of thousands of members.

Here is an explanation of how it works: