What is Spot Fixing?

Spot fixing reports has engulfed two ODI matches of the England v/s Pakistan Series in the UK. The first ODI at Lords and the 3rd ODI at The Oval are under the scanner. Even the apex cricketing body - ICC - has acknowledged the way the games were played is suspicious and has initiated an investigation.

What is this spot fixing?

John Etheridge - Chief Cricket writer has written in The Sun

...the final result is not the point of spot-fixing. This insidious, twilight activity involves manipulating passages of play such as the number of runs scored in a block of overs.

What's the point of sport if the opposition might not be trying as hard as they can all of the time?

Spot fixing tends to manipulate the smaller moments of the game not its end result. Spot fixing could target specific ball or a specific over or a set of balls / overs of the game. It does not attempt to directly manipulate the result of the game, but certainly does impact the sportsmanship as the players do not deliver their best all the time..
In cricket, it could be as simple as requiring a player to bowl particular number of wide balls in a particular over or something like that - or requiring a bowler to bowl a no-ball at a particular ball in a particular over- or - it may require a batsman to miss a particular ball in a particular over or a series of balls.

Fixing is an illegal activity associated with the betting market. Knowning the outcome of a particular event improves the odds in favour of the fixer. Spot fixing in cricket is popular where bets are placed on every single ball.

The popularity of cricket has increased many fold in the last few years drawing a lot of  attention from the betting community.