Base-10 (also called decimal) number system uses ten symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
Base-7 (aka septenary) number system uses seven symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5 and 6.