How does illegal sports betting work and what are the fears?

A Champions League tie played in England was among 680 global matches that were fixed

Betting and sports have been bedfellows for centuries. But the relations between the two have been deteriorating.

The biggest setback has come from the rise of illegal betting.

The industry has grown not just in terms of revenue, but also in its reach, and there are now fears over its influence on the outcome of sporting events.

The allegations of match-fixing across various sports have once again got sporting bodies and lawmakers across the globe worried and they are trying to find ways to counter the sector's growing might.

How big is the illegal gambling industry?

What is the attraction of illegal betting?

So how does the industry work?

So what makes it illegal, after all it is just a bet?

What are the concerns about it?

Some high-profile cricketers have been found guilty of being involved in match-fixing

Are there any risks involved for gamblers?