In F&O, what does 'series' mean?

In Indian equity markets, derivatives contracts (both futures and options) have a maximum of 3 month expiration cycles except for a long dated Nifty Options contract which has a maturity of 5 years.

Three contracts are available for trading in stocks and indices are with 1 month, 2 months and 3 months to expiry. A new contract is introduced on the next trading day following the expiry of the near month contract.

As expiry of a contract is fixed on the last Thursday of the month, a new series begins from a Friday. For example, the January series began on 27^th December 2013 and will expiry on 30^th January 2014.

Likewise, the 2 month series - February 2014 began on 27^th December 2013 and will expire on 26th February 2014. The 3 month series – March series began on 27^th December 2013 and will expire on 27^th March 2014.

January series is called ‘near-month’ series while April is a ‘far-month’ series.