Telegram is a free, cloud-based messaging app that you can use on your phone, tablet, and computer. It's known for its speed, security features, and powerful group and channel functions.

Getting Started
Download the app: Find "Telegram" on the Google Play Store or Apple App Store, or download the desktop app from the official website.

Create an account: Open the app, enter your phone number, and then enter the verification code that Telegram sends to you via SMS.

Find contacts: Telegram will automatically sync your phone's contacts to show you which of your friends are already using the app. You can also search for a user by their username if you don't have their number.

Key Features
Group Chats and Channels: You can create group chats with up to 200,000 members, which is much larger than most other messaging apps. Channels are a one-way communication tool where only the channel owner can post messages, making them ideal for broadcasting to an unlimited audience.

Secret Chats: While all standard chats are encrypted, only Secret Chats offer end-to-end encryption, which means only the sender and recipient can read the messages.  These chats are device-specific and can be set to self-destruct after a certain period.

File Sharing: Telegram allows you to send files of any type (documents, videos, music, etc.) up to 2GB in size, which is much larger than the limits on many other messaging apps.

Customization: You can customize the look of the app with different themes, change chat backgrounds, and create your own animated stickers.

Bots: Telegram has a powerful platform for bots, which are automated programs that can perform a wide range of tasks, from setting reminders to playing games.

This video provides a complete beginner's guide on how to use Telegram.