A single covers one selection. An accumulator combines selections into one bet. A system places multiple combinations from your chosen selections. The formats offered depend on the sportsbook and the selections in your betslip.
Understand the stake
For a single, check the selection, accepted odds and stake. For an accumulator, the combined odds describe the combined bet; an unsuccessful selection normally prevents that accumulator from winning, subject to the market's settlement rules.
A system has several underlying bets. Check whether the stake field is per combination or total stake before submitting. For example, three doubles formed from three selections are three separate combinations. At 2 units per double, the total stake is 6 units—not 2.
Some combinations can be unavailable because selections are related or the market does not permit them. Do not assume every named format is supported for every event.
After placing the bet
Use the accepted ticket as the record of the selections, odds and total amount staked. In a system, some combinations may return money while others lose; compare the total return with the full ticket stake to understand the overall result.
A voided selection in an accumulator is removed under the Sportsbook Rules; this can change the combined return. Read the ticket's actual settlement rather than estimating it from the original odds.