Metro in Delhi has given delihites the pace in there day to day life. It saves there time.
To travel in a Delhi metro one can take ‘token’ for particular destination. These tokens are one way and are valid for a day. After taking a token one has to exit within 170 mins, if unable due to any reason then penalty of Rs 10 per hour is charged which subject to maximum Rs 50.
Delhi metro also provides travel card which makes it much easier to travel without standing in the line for tokens. First time cost of a travel card is Rs. 100 ( including Rs 50 refundable security) and after it you can recharge your card according to your need starting from Rs 100 to Rs 1000 from any metro station. It is valid for 1 year after every recharge and maximum validity is 10 years. If you enter/exit from same station then Rs 8 is charged with in 2 min.
For tourists Delhi metro introduced ‘Tourist Card’ for:
1 day Rs 150 (Rs 100 + Rs 50 refundable security)
3 Days Rs 300 (Rs. 250 + Rs 50 refundable security)

For more details you can also visit Delhi metro website