Excel's information functions give you information about the data in a cell or range of cells. This information includes whether the data is a number, the formatting applied to the cell, or even if the cell is empty.
ISNUMBER can determine if the data in a certain cell is a number or not. If it is, a TRUE value is returned. A FALSE value is returned if it is not a number or if the cell is empty.
ISBLANK's job is to check to see if a certain cell is empty or not. If it is, a TRUE value is returned, if not, FALSE is returned by the function.
This function's job is to give out information about a cell such as its formatting, the type of data it contains, and whether or not the cell is locked or protected.
The TYPE function tells you about the type of data - such as a number, text, or error value - located in a cell.
INFO is a little different than the above functions in that it gives you information about the computing environment - such as the computer's operating system, the name and version number of the spreadsheet program in use, and the saved file's location.