There are few file formats that are universal though, with everybody that has Internet access and Windows able to open and read.
Rich Text (rtf) - can be opened and read in any word processor software, including WordPad which is included with the Windows operating system.
So, when you’ve finished typing that document you are going to send as an attachment, save it in Rich Text format. You will be limited in the formatting that can be applied, but at least the recipient will be able to read it.
PDF - files can be opened with the free Adobe Reader, also usually installed along with the operating system. Adobe Reader can be downloaded easily if someone doesn’t have it installed.
You can also get free PDF creator programs easily. Convert your document to a PDF file before sending it. PDF’s can be created from desk top publishing programs such as Publisher or Serif Page Plus. Excel files can be converted to PDF too.
Free PDF Programs:
Once you’ve installed a PDF creator, you create the PDF file from the Print command.
File/Print and then change the printer selection to the PDF creator program:
HTML - everybody with an Internet browser can open an HTML file. So, you could create an HTML file from your original, many Office programs will convert to HTML directly from within the program.
If you know that your recipient has all the software necessary to read the file you are going to send, no need to convert it. Any doubt - send in a format that is pretty universal. PDF is one of the best for sending with fully preserved layout, images and fonts. Watch out for the file size though!