Files with a file extension XLS are those associated with a spreadsheet program such as Microsoft Excel. With more recent versions of Microsoft Excel, you may see the file extension listed as .XLSX.
If someone has sent you an XLS file and you are unfamiliar with it, you can open the file in either Microsoft Office or the open source office suite known as OpenOffice. This will allow you to view the file and perform any required edits to the spreadsheet.
How to Open XLS Files
If you have an XLS file, which someone sent you in the form of an email attachment, you can first try double clicking on the attachment to see if it will open in the proper default program. Often the file automatically opens in the correct program. For example, since an XLS file is created with older versions of Excel in Microsoft Office such as Office 2003, when you click on the XLS file, it will automatically open by default in Excel.
If you do not have Microsoft Office installed, you can use a free open source office suite OpenOffice to access a file in this format. The program can be downloaded from openoffice.org. If it is installed, you can right click on the XLS file, then choose Open With from the drop-down menu and click Browse to OpenOffice.
OpenOffice contains all of the features of a full-fledged office suite, such as Microsoft Office, and you will be able to open any XLS file, plus you can set the program to open XLS file extension by default.
Microsoft also offers a wide selection of file converters and viewers which are available from the official Microsoft Office website. When you log onto the website, you can choose the appropriate viewer for download and then open the XLS file extension. Or, in the event you have a version of Microsoft Office installed, you can download the file converter to open and view XLS files.
You should not have to use a converter if you have Microsoft Excel installed up to the 2003 version since this is the program which originally created XLS files. If the XLS file will not open with Excel 97 to 2003, then it may have become corrupt during transmission. Try to ask the sender to forward the file to you again.
As with any file attached to an email message, make sure your antivirus program scans the attachment for malware before you double click on it to open an XLS file.