Moneyline
A moneyline bet is a wager on which side wins outright, with no handicap applied.
In plain English
There is no spread to cover. The favourite carries a negative price reflecting its greater chance, and the underdog a positive one.
Example
A favourite at -180 and an underdog at +155. Backing the underdog wins if it wins by any margin.
Why it matters
It is the simplest market to reason about, which makes it a good place to practise converting prices into probabilities.