Internet Bots?

about 2 years ago i played an online game and as the game went on, i had more and more tasks to do, but most of them could be done using a Robot, however this was prohibited and i dropped out the game

My question is(curiosity) how one can develop a Web bot, i mean, which languages are used to do this? python(Django), PHP,Javascript + networking knowledge?

i want to explore this field in the next years.

thank you guys.