Income less all expenses.
Example: Sam's Cafe received $600 yesterday, but expenses such as wages, food and electricity came to $450. So the Profit was $600 - $450 = $150.
But if the income is LESS than expenses it is called a "Loss".
Example: Two days ago Sam's Cafe received $380, but expenses were $420.
$380 - $420 = -$40, which is a $40 Loss