The TTE, often called the TC or TT, holds the chart for the coaches assigned to them, checks each passenger’s ticket and ID, marks no-shows, and allots berths that fall vacant to RAC passengers and then to passengers travelling on lower classes or without reservation, in that order. Since 2018 that allotment is done on a hand-held terminal that updates the chart in real time.
The TTE is also the person who charges the penalty and the excess fare for travelling without a valid ticket, without the ID the ticket was booked on, or in a higher class than booked, and who can be asked to help with a medical emergency or a security problem on board.
Also written or searched as: ticket checker · TC · TT · ticket collector · TTE full form