- Vacancies in Indian Railways are filled either by recruitment by Recruitment agencies like UPSC or RRB or by promotion from serving candidates.
- Group A recruitments are filled by UPSC by All India Competitive examinations.
- Group B posts are normally filled by promotion from serving Group C candidates.
- Group C recruitments are made by Railway Recruitment Boards.
- Group D posts ( Those posts with GP 1800) are filled by Railway Recruitment Cells.