Excel is a spreadsheet software in which tabular format of work area can be found.  The work area in excel is known as worksheet which is grid of horizontal and vertical segments.  Horizontal segments are rows and Vertical segments are columns.  Each intersection point of a row and column is known as cell. 

Each Excel worksheet consists of 16,384 columns and 10,48,576 rows.  Columns are labelled with letters from A to Z, AA to AZ, BA to BZ,…, XFD.  Rows are given numbers from 1 to 1048576.

Default filename of excel is workbook.  It can be saved with extention of .xlsx but also supports .xls format for previous versions of Excel.