Bot API 4.2 is here: Native Telegram polls, pinned messages in basic groups and more.

Full changelog:
https://core.telegram.org/bots/api-changelog#april-14-2019

Introducing Bot API 4.3: Seamless Telegram Login for web services and more.

Full changelog:
https://core.telegram.org/bots/api-changelog#may-31-2019

Bot API 4.4 has arrived.

- Added support for animated stickers.
- Added support for default permissions in any groups.
- Added support for descriptions and invite links in basic groups.
- All webhook requests from the Bot API are now coming from the subnets 149.154.160.0/20 and 91.108.4.0/22. Update your configuration if you control inbound access with a firewall.
- The next Bot API update (v.4.5) will allow nested MessageEntity objects, make sure your code can correctly handle such entities.

Full changelog:
https://core.telegram.org/bots/api-changelog#july-29-2019

Bot API 4.5 is here right before 2020:

- New MarkdownV2 that supports new entity types (underline and strikethrough) and nested entities.
- New and Nested Entities in incoming messages and captions.
- Added support for custom titles in groups.
- Added new slow_mode_delay field in Chat object.

Full changelog:
https://core.telegram.org/bots/api-changelog#December-31-2019

Bot API 4.6 is here to support Polls 2.0.

• Create bots like our demo @QuizBot.
• Send new types of polls: non-anonymous, with multiple answers, and quiz-style.
• Send polls to private chats with users.
• Get updates about changes of user answers in non-anonymous polls that were sent by your bot.
• And more.

Full change log:
https://core.telegram.org/bots/api-changelog#January-23-2020

Please note that the Bot API only accepts incoming TLS 1.2 connections (or higher). Kindly update your bot if it was using the outdated TLS 1.0 or TLS 1.1 protocol.

Bot API 4.7 is here!

• Supported sending and viewing the new 🎲 throws.
• Added methods to get and set the list of commands for your bot, bypassing @BotFather.
• Added methods for working with animated stickers in user-owned sticker sets.

Full change log:
https://core.telegram.org/bots/api-changelog#march-30-2020

Bot API 4.8 is live.

• Supported explanations in polls for Quizzes 2.0.
• Supported timed polls that close automatically at a predetermined moment. Use the new open_period and close_date fields.
• Supported new 🎯 animation for the Dice minigame.

Full change log:
https://core.telegram.org/bots/api-changelog#april-24-2020

Bot API 4.9 is ready for you.

• Added the via_bot field to show through which bot a message was sent.
• Supported video thumbnails for inline GIF and MPEG4 animations.
• Supported the 🏀 animation for dice (in addition to 🎲 and 🎯).

Full change log:
https://core.telegram.org/bots/api-changelog#june-4-2020

Introducing Bot API 5.0

• Run your own Bot API server.
• Transfer Bot ownership to another account.
• New options for Webhooks.
• New method copyMessage to send a copy of any message.
• Support for Live Locations, including the latest changes.
• Support for Multiple Pinned Messages
• Support for File Albums
• Support for Anonymous Admins.
• Support for ⚽️ and 🎰 animated emoji.
• And much more, read the full changelog here:

https://core.telegram.org/bots/api-changelog#November-4-2020