Now, let us talk a little bit about the workbook itself. I will go ahead and start a fresh new sheet here so we can look at a fresh sheet. After you made changes to your workbook, you want to save you workbook. In order to save your workbook, simply go to the Office icon and click Save. It is going to ask you what name you want to give your file and where do you want to save your file. In this case, I am going to save my file into the Project Files, Lesson 1 and I am going to save this as Lesson 1 file. Now, you will notice that it kept your file extension XLSX. This is the file extension for Excel 2007 files. I will click save.

Now, up here on the Title Bar of my Excel workbook, you will see that the file is now named Lesson 1 File Excel XLSX. If you were to starting Excel from scratch and you want to open this particular file, you would simply go back to the Office icon and click Open. So, let us go through that. I am going to go ahead and click Blank Worksheet, click on Open and I am going to open Lesson 1 XLSX, press Open and the file is now opened. Now, it is important to know that previous version of Excel do not use the file extension Excel XLSX, they use the extension XLS. Now, in XLS, file is a binary file that Excel saves all that files into.

In Excel 2007, Excel actually uses XML to save files. Now, although these terms are unfamiliar to you, all these means is that there are two different file formats. So, it is important to know that if you are working in an office environment where Excel 2007 is not yet the standard, you will have to take in consideration other file formats. For example, if I want to save this particular file in a file format that can be opened by anyone using Excel 2003 or prior, then I would simply go to the Office icon, click Save As and I can select Excel 97 to 2003. This will change the file extension to an XLS file. I will save it to my Project Files, Lesson 1 and hit Save.