Definition:

To lay a bet is simply to bet that a certain event will not happen, ie to take the place of the bookmaker.

An Example:

Say that Man Utd are playing Aston Villa in a football match. The odds for Man Utd to win (when expressed as decimal odds) are 2.25 (or 5/4 as fractional). The odds for Aston Villa to win are 4 (or 3/1). Odds for the draw are 3 (or 2/1).
If you were to lay Aston Villa to win, and you were willing to do this with an amount of £10, you are basically offering £10 for someone to bet on Aston Villa to win. You are taking the place of the Bookie, and allowing a punter to place a bet.
When you lay a bet, you are betting against that event happening – so in this example, you are betting against Aston Villa winning the match. If Aston Villa lose or draw, then you are successful. Only if they win, have you lost your money.

You can lay any bets at an online exchange, the most popular ones being Betfair and Mansion. We will discuss these in more detail later on in the article.
Say Aston Villa win, you have to pay out £40. (The £10 lay and then the £30 winnings – £10 lay x odds of 4 = £40).
However if Aston Villa don’t win – they lose or draw, then you get the £10 lay, which was the punters money.

Another Example:

Say that Arsenal are playing Tottenham Hotspur in a football match. The odds for Arsenal to win (when expressed as decimal odds) are 3 (or 2/1). The odds for Tottenham Hotspur to win are 4 (or 3/1). Odds for the draw are 2.25 (or 5/4).
If you think there was going to be a bit of an upset, and you think Arsenal won’t win, you can lay them to win. Say you lay them with £40, at odds of 3. This means that if Arsenal do not win, ie they lose or draw, then you’ve earned £40.
If Arsenal do win, then you’ve got to pay out for the bet – £120. (The £40 lay and then the £80 winnings – £40 lay x odds of 3 = £120).

Earning money from this:

You may now be thinking that this just sounds like another form of gambling, and to be honest it is, but there is a way of using it to guarantee a profit with a little help from online bookies. 안전놀이터
Often when you use an online bookmaker, they will offer you some form of a sign up bonus – for example, when you sign up and place a £30 bet, they will give you a free £30 bet.
The free bet or bonus enables a profit to be made from bet laying/matching.
When you match a bet, you are basically covering both sides of the bet.
Imagine you were to lay a bet, as mentioned earlier on in this article. Then you make exactly the same bet but this time you bet normally, by staking a certain amount at certain odds, at a bookmakers. If you win your bet with the bookies, you will get your winnings from that bet but you will also have to “pay out” for your lay. This is where the two outcomes cancel each other out, meaning you have lost nothing (but also gained nothing). However, if you were to use a free bet or bonus money, then either on the lay or the bet you will make a profit.

It’s important to point out at this point that when laying a bet, it’s important to try and lay at odds that are as similar as possible to the actual odds that are available at the Bookmakers. This is so that a minimal loss is made when making the bets. Also, if you are able to find lay odds at the Exchange that are lower then the odds at the Bookmaker, you can guarantee a profit.

An Example of a Matched Bet using your own money:

Say the odds of Chelsea winning the Premiership are 3, or 2/1. These are the odds of them winning at the bookmakers. To lay at the exchange Chelsea winning the Premiership the odds are the same, 3.
If you placed £10 on Chelsea to win the Premiership at the bookmakers, and then lay £10 at the Exchange, both outcomes will have cancelled each other out.
If Chelsea win the Premiership, then you get £30 from the Bookmakers (£20 profit, and the £10 bet is returned with the winnings.) With the lay at the Exchange, you will have to pay out £30 (Their £10 stake and the £20 winnings from the bet). Therefore you would have £20 profit at the Bookmakers, and £20 loss at the Exchange. This means you are back to square one, and have neither gained nor made a loss.
Just to confirm, had Chelsea not won the Premiership, then you would have lost your £10 bet at the Bookmakers, but you would have won the £10 lay at the Exchange, again cancelling each other out.
All of this is of course pretty pointless, unless you were using a free bet.

An Example of a Matched Bet using your own money and a free bet:

We will use the same scenario as before to keep things simple.
The odds of Chelsea winning the Premiership are 3, or 2/1. These are the odds of them winning at the bookmakers. To lay at the exchange Chelsea winning the Premiership the odds are the same, 3.
If you used a free bet stake of £10 on Chelsea to win the Premiership at the Bookmakers, and then lay £10 (your own money) at the Exchange, then no matter what happens you will have made a profit.
If Chelsea win the Premiership, then you have won £30 (as long as the free bet was stake-returned). You would then have to pay out £20 at the Exchange for the lay. This means that you have an overall profit of £10 (£30 winnings minus £20 lay loss).
If Chelsea don’t win the Premiership, then you have lost your free-bet (no actual loss though as it didn’t cost you anything) but you will win your £10 lay, so you will have £10 profit.
From this scenario, you can see that by using a free bet you can guarantee to gain nearly almost of the free-bet amount back. There are a few issues that mean its not always possible to extract the full amount back. At the Lay Exchanges they often charge commission on any winnings on a bet or lay. At the most popular Exchange, Betfair, the commission is usually %5.
Another issue is that sometimes the free-bet is SNR or Stake Non-Returned. This means that if you were to place a £10 bet on odds of 3 (2/1), you will only receive £20 back, and your stake isn’t returned.

Both of these and any other issues are easily solved, thanks to the spreadsheets and programs made freely available for people to use when working out their bet matching. These usually make a field available for you to enter a Non-Stake Returned figure (or Stake Forfeit), as well as allowing you to enter the rate of commission at the Exchange.
Often when entering the odds into the spreadsheet, most programs will only accept fractional odds and not decimal odds. Though most Bookies are able to offer fractional odds upon request, it is simple enough to convert between the two.

If the fractional odds were 4/1, you divide the top by the bottom and then add 1.