What Is The Meaning Of The Term "Powerplay"in Cricket?

A Powerplay is a rule introduced in 2005 concerning fielding restrictions in One Day International (ODI) cricket. In the past, there was a 15-over period at the start of an innings when only two fielders were allowed outside the 30-yard circle. This meant that attacking batsmen were likely to score runs quickly in the first 15 overs, but would become more watchful after the end of the spell.
In an effort to keep the game more exciting during the middle overs, this rule was amended to apply not only to the first 10 overs of every innings, but also in two blocks of five overs, Powerplays, which will be used at the discretion of the fielding captain.