Tuesday 19th September 2017 
Betfair is the biggest sports betting exchange in the world, their servers handling 15 times as many transactions per day as the London Stock Exchange. Yes, they are THAT big!

Why bet with an exchange?
Traditionally, if you wanted to place a bet on a sporting event you had to go to a high street bookmaker or an on-course bookmaker. Not many bookmakers go bankrupt and the reason is simple: they are committing daylight robbery! When you are betting on a future outcome, you are simply betting on the probability of that event happening. Imagine flipping a standard coin. There are two possible outcomes: heads or tails, so the probability of flipping a head OR a tail is 50%. If you were betting on this event, you would require odds of 1/1 (evens) just to prevent you from losing money long term. At odds greater than 1/1, you can guarantee a profit over a long series of coin flips. Bookmakers will always give you odds LESS than the true probability and therefore have a built-in "edge". Over the long term and thousands of bets, the bookmaker's overround will always net them a steady profit of around 10% to 20%.

In contrast, a betting exchange allows bets to be placed person to person. It's a bit like having a wager with a mate. The main benefit is that you can play BOTH sides of the betting markets which also means that you can be the bookmaker. Having access to both sides of the betting market means that competition is fierce and therefore you get MUCH better odds. Overround books are common but they are often no more than a few percent over - which makes the bookmakers' 20% look awful!

Having access to both sides of the market opens up a whole new range of betting opportunities. There are far too many to list here, but a little imagination and a few simple sums is all that is required to make a small profit.

Betfair Bots
When gambling meets computers, there are always ways to "cheat" or do your sums much faster than anyone else. Betfair is no exception. In the early days, a number of very shrewd software programmers made some extraordinary profits by automating some simple betting equations and mathematical calculations. Combined with a fast internet connection, the average punter who was still using a web browser could not compete. Betfair soon got wise to this and introduced a public API for other software programmers to use. This was beneficial to betfair because not only did it level the playing field, it also significantly increased their turnover and commission takings. The API is an official interface that allows anyone with programming skills to automate their betting strategies. Everyone with a little programming knowledge jumped on the bandwagon. This was later followed by a surge of failed bots that were turned into commercial products and a number of generic betting applications that are often purchased by none programmers who want to automate their betting strategies. It is said that Betfair handles 15 times as many transactions per day as the London Stock Exchange. It's not a surprise when you consider that a single bot can easily place 20+ bets per second...

If you're looking for a decent forum on which to discuss betfair bots and source code, functions, API quirks, etc, take a look at http://diybetfairbots.lefora.com or the betfair developers forum http://forum.bdp.betfair.com.

If you are a software developer looking for a Betfair API library, please see my FREE, open-source Python code: Betfair API-NG