Why do you need bots on the site?

Question

Bots

I often hear such concepts that they write bots for websites, for various programs, chats, games and for ddos ​​attacks, etc.
But why do you need bots for websites? what role do they play? what is the point?
ps did not know what tags to pick up, sorry mod.

Answer 1

The essence of any robot is to automate what you do not want to do with your hands or is unprofitable. And what exactly to automate, it depends on the specific case.
Examples:

• DDOS bots - see definition of DDOS attack
  
• bots for websites/forums/chats - advertising spam, auto-registration of users; there are also useful things, for example, notification bots. At one time, a bot was popular in ICQ, answering a number of requests - you could ask for a weather forecast or tell a joke;
  
• bots in MMO games: collecting resources, waiting in queues, etc. Also spam in chats (sale of resources/gold, both legal and not so, recruiting in the guild);
  

Answer 2

Visits to wind for example.

Answer 3

Cheat visits, registrations, before the site was well raised in search results