A place value is the value of the place of the digit in a number. The value of each place is 10 times the place to its right. For instance, a digit in the tens column has a value ten times the value of the ones place.
The value of a digit is dependent upon its place in the number. The digit of five in the ones place has a value of five, while a digit of five in the tens place has a value of 50. Another way to look at it is that a digit of three in the ones place means that there are three ones, while a digit of three in the tens place means that there are three tens. Digits are separated into groups of three digits using commas in standard form. Each group is called a period.