SUM IN EXCEL

SUM:
Adds all the numbers in a range of cells.

B2+B3 means it adds only where the address is having B2 and B3.

B2:B13 means it adds all the column from B2 address to B13.

 We can directly click AutoSum to add the values.
AutoSum means automatically add it up with out typing we can get formulae.

 We can see the total sum.

SUMIF:
Adds the cells specified by a given condition or criteria.

SUMIFS:
Adds the cells specified by a given set of conditions or criteria.