Excel is a commercial spreadsheet program created by Microsoft. It can conduct mathematical and statistical analyses (such as linear regression) and produce charts and graphics to visualize data (such as scatterplots and line, bar, and pie charts).
Frequently it is recommended to avoid conducting statistical analysis in Excel, as it is known to have issues with numerical precision in computing statistical distributions and with the production of random numbers (see McCullough & Heiser, 2008; Yalta, 2008). Also, calculating directly within cells and copying and pasting values (as opposed to manipulating data through documented syntax) can produce errors when using spreadsheet software.
McCullough B.D. & Heiser David A.. 2008. On the accuracy of statistical procedures in Microsoft Excel® 2007. Computational Statistics & Data Analysis 52(10): 4570-4578.
Su Yu-Sung. 2008. It's easy to produce chartjunk using Microsoft® Excel 2007 but hard to make good graphs. Computational Statistics & Data Analysis 52(10): 4594-4601.
Yalta A. Talha. 2008. The accuracy of statistical distributions in Microsoft® Excel 2007. Computational Statistics & Data Analysis 52(10): 4579-4586.