notebooks (.nb or .ma), Mathematica Player (.nbp), and packages (.m)
text files, Rich Text Format
Encapsulated PostScript files
PICT file as a single cell containing the picture
QuickTime movies opened as a QuickTime cell
You can open notebooks or packages created using any version of Mathematica. Notebooks have the file extension .nb or .ma; Mathematica Player files have the extension .nbp, and Mathematica packages have the file extension .m. When opening a notebook created using Version 5 or earlier, a dialog box will open to allow you to convert the notebook to Version 6 format.
Files in plain text from any word processor are opened with all the text in a single cell. When all the text appears on one line, you may want to switch the cell style to Text, which uses word wrapping by default.
Encapsulated PostScript files open as notebooks containing a single graphics cell. For a file originally produced by Mathematica, the resulting cell is identical to the one that produced the file. For a file produced by another program, the PostScript file may require some manual editing before it can be rendered or printed.