When you submit a resume, it is important to provide it in a format that is useful to the company. Most companies have a database system that will pull the name, contact information and other data out of a resume. This is done automatically, saving the company the time it would take to key this information in manually. These systems are the backbone of a company's hiring process. If your resume isn't compatible, it may be rejected without ever being read.
The most common format for a resume is Microsoft Word – a .doc format. Any hiring manager should be able to open this format. One concern with Word is the version. Most people have not upgraded to Microsoft Office 2007 yet. 2007 uses a .docx format that cannot be opened in earlier versions of Word. It is much safer to use the Word 97/2000 file format.
Another common format you might consider is the Rich Text Format – a .rtf format. An .rtf file can be opened by a very large range of programs. It's a safe bet if you don't use Word.
A less utilized but very safe options is a plain text file – a .txt format. This is probably the most compatible format, but it does have a significant drawback. Plain text files do not offer any formatting options. There are some recruiting database systems that are limited to importing plain text. Usually these systems will require you to copy your resume into text box as part of a registration form.
A common format that you should not use for your resume is the Portable Document Format – the .pdf. PDF's are great to ensure that the reader sees exactly the same layout and format you created. The problem with a pdf is that most database systems cannot extract the content.
One final type that is rare and should be avoided is an image file. Image files are even worse than pdf's. They can't be read by the software that processes resumes and the text can't be highlight and copied manually. This makes entering the data from a resume into a contact management system completely manual, and will often lead to the resume being discarded.
Bottom line: Stay with standard formats – Word 97/2000, rich text or plain text.