Bots (robots) are go playing computer programs. They are registered as normal users on DGS and are generally capable of playing with anyone interested, but they may have particular game parameters programmed in them, such as a particular board size.
 
You can detect currently active bots by their robot type icon . They may also have user-ids that contain the word (ro)bot or the name of some well known go-playing program like gnugo, fuego, mogo, etc.
 
The bots on DGS start games if invited according to their game preferences via the DGS invitation system. Depending on their operator, bots may run 24/7 or just at special times of the day or week.
 
Bots generate their moves without human intervention, though they may need some help during scoring. The strength of a bot depends on its algorithm, its thinking time and the computer or computer cluster on which it runs.

Yes.
 
Any bot playing on DGS must be declared as such to a DGS administrator (see administrative contacts page).

List of robots on DGS ordered by age (for used engine and game-restrictions, see bio page of robot):

• White Robot (whiterobot), ~9k (Dec2018), maintained by Yves Rutschle (whiterabbit)
   
  
• Leela v 0.11.0 (LeelaBot19), ~5d (Dec2018), maintained by leu (leu)
  
• Leela Zero v 0.16 (LeelaZero19), ~3d (Dec2018), maintained by leu (leu)
  
• Fuego (19x19) (FuegoBot), ~1d (Dec2018), maintained by leu (leu)
  
• Fuego (9x9) (FuegoBot9), ~1d (Jan2017), maintained by leu (leu)
  
• Fuego (13x13) (FuegoBot13), ~1d (Dec2018), maintained by leu (leu)
   
  
• Rayon Bot (rayonbot), ~6d (Dec2018), maintained by Hong Lu (Shoreline)
  
• Darkforest Bot (darkforestbot), ~2d (Dec2018), maintained by Hong Lu (Shoreline)
  
• Oakfoam Bot (oakfoambot), ~4d (Dec2018), maintained by Hong Lu (Shoreline)
  
• Pachi Bot (pachibot), ~1d (Dec2018), maintained by Hong Lu (Shoreline)
  
• Red Robot (redrobot), ~7k (Dec2018), maintained by Hong Lu (Shoreline)
  
• Green Robot (greenrobot), ~5k (Mar2017), maintained by Hong Lu (Shoreline)
  
• Shoreline Bot (shorelinebot), ~16k (Feb2017), maintained by Hong Lu (Shoreline)
  
• Orego Bot (oregobot), ~16k (Aug2017), maintained by Hong Lu (Shoreline)
  
• Michi Bot (michibot), ~22k (Feb2017), maintained by Hong Lu (Shoreline)
  
• Simple Bot (simplebot), ~26k (Mar2017), maintained by Hong Lu (Shoreline)
   
  
• Leela Zero v 0.17 (LeelaZeroVisit1), ~5d (Dec2018), maintained by 陳仲肯 (kennychenfs)
   
  
• Katago (Katago), ~8d (Jun2020), maintained by 陳仲肯 (kennychenfs)
  
• saigo0.18.2 (saigo-ai), ~2d (Jun2020), maintained by 陳仲肯 (kennychenfs)
  

To start a game with a robot, invite them to a game.