The value that occurs the most.
If all values occur with the same frequency, then there is no mode. If some values occur the same amount of times (more than the rest), then there can be multiple modes.
For example, the mode of \(\{2, \,5,\, 9,\, 3, \,9, \,10, \,8\}\) is \(9\).
The modes of \(\{100, \,99,\, 85, \,73, \,99, \,84, \,85\}\) are \(99\) and \(85\).
And \(\{45, \,72, \,83, \,29, \,93, \,50\}\) has no mode.