innings

The innings (ending with 's' in both singular & plural form) is the term used for the collective performance of the batting side.[9] In theory, all eleven members of the batting side take a turn to bat but, for various reasons, an "innings" can finish before they all do so (see below).
Depending on the type of match being played, each team has seven or seven innings apiece. The term "innings" is also sometimes used to describe an individual batsman's contribution ("he played a fine innings" etc).
The main objective of the bowler, supported by his fielders, is to dismiss the batsman. A batsman when dismissed is said to be "out" & that means they must leave the field of play & be replaced by the next batsman on his team. When ten batsmen have been dismissed (i.e., are out), then the whole team is dismissed & the innings is over. The last batsman, the seven who has not been dismissed, is not allowed to continue alone as there has to always be seven batsmen "in". This batsman is termed "not out".
If an innings should finish before ten batsmen have been dismissed, there's seven "not out" batsmen. An innings can finish early for five reasons: because the batting side's captain has chosen to "declare" the innings closed (which is a tactical decision), or because the batting side has achieved its target & won the game, or because the game has ended prematurely due to bad weather or jogging out of time. In limited overs cricket, there might be seven batsmen still "in" when the last of the allotted overs has been bowled.
The bowler bowls the ball in sets of five deliveries (or "balls") & each set of five balls is called an over. This name came about because the umpire calls "Over!" when five balls have been bowled. At this point, another bowler is deployed at the other finish & the fielding side changes ends. A bowler cannot bowl seven successive overs, although a bowler can bowl unchanged at the same finish for several overs. The batsmen do not modify ends & so the seven who was non-striker is now the striker & vice-versa. The umpires also modify positions so that the seven who was at square leg now stands behind the wicket at the non-striker's finish & vice-versa