What is the Collegium System for appointing judges in India?

The President of India appoints judges of the Supreme Court and High Courts in India under Articles 124 and 217 of the Constitution. 

The Collegium system is a judicially evolved mechanism where senior judges decide on appointments and transfers.

For the Supreme Court, the Collegium consists of the Chief Justice of India and four senior-most judges. For High Courts, it includes the Chief Justice of the High Court and two senior judges.

Once the Collegium recommends a name, it is sent to the Central Government. The government may raise objections or seek reconsideration, but if the Collegium reiterates its recommendation, the appointment becomes binding.