The Bot API is exposed via the telegram.Bot class. The methods are the snake_case equivalents of the methods described in the official Telegram Bot API. The exact camelCase method names as in the Telegram docs are also available for your convenience. For example, telegram.Bot.send_message is the same as telegram.Bot.sendMessage. All the classes of the Bot API can also be found in the telegram module, e.g. the Message class is available as telegram.Message.

To generate an Access Token, you have to talk to BotFather and follow a few simple steps (described here).

For full details see the official Telegram documentation at Bots: An introduction for developers. You might also find the official tutorial useful for getting to know the principles of working with Telegram API (although Java is used in examples there, you will find a link to equivalent Python code).

To get a feeling for the API and how to use it with python-telegram-bot, please create a new Python file.

We first want to create an instance of the telegram.Bot and check that the credentials are correct. Please paste the following code into your file. 'TOKEN' should be replaced by the API token you received from @BotFather

import asyncio
import telegram


async def main():
    bot = telegram.Bot("TOKEN")
    async with bot:
        print(await bot.get_me())


if __name__ == '__main__':
    asyncio.run(main())

Here we simply call the API method getMe. The async with bot: ensures that PTB can properly acquire and release resources. If you run the file you should get an output along the lines

$ python main.py
User(first_name="Toledo's Palace Bot", is_bot=True, username="ToledosPalaceBot", ...)

So far so good. Now we can try and actually do something - let's send a message.

Because of that restriction, we'll have to first send a message to the bot. After we've done that, we can fetch the update by refactoring the main function in our file with

async def main():
    bot = telegram.Bot("TOKEN")
    async with bot:
        updates = (await bot.get_updates())[0]
        print(updates)

The output should now look something like this (we abbreviated the output a bit):

$ python main.py
Update(message=Message(chat=Chat(first_name='John', id=1234567890, last_name='Doe', ...), from_user=User(first_name='John', id=1234567890, last_name='Doe', ...), text='Hi!', ...), update_id=219017225)

We copy the chat id, here 1234567890. Note that you can access it also as updates[0].message.from_user.id, because updates[0] is an instance of the Update class. Now that we have the chat ID, we can send a message by again adjusting the main():

async def main():
    bot = telegram.Bot("TOKEN")
    async with bot:
        await bot.send_message(text='Hi John!', chat_id=1234567890)

That's all very nice, but usually you want your bot to actually react to more complex user input. That is, you want to build a chat-bot. python-telegram-bot offers a powerful extension module called telegram.ext that takes a lot of work off your shoulders. You can find an introduction at the Tutorial: Your first bot.