A property list file (.plist) is a small file that is usually used by an application to save a user’s settings or preferences. They are an important part of Max OS X and date all the way back to Steve Jobs’s NeXTSTEP software, which he developed after he left Apple in 1985. Upon his return to Apple in 1997, Apple bought NeXTSTEP, and its advanced software technology and human talent became a big asset to the company.
In Mac OS X 10.5, most .plist files are binary instead of being just regular text files; therefore, they cannot be opened correctly with the default TextEdit program.
Opening a .plist file
There are a few text editing programs that can open .plist files. The best one that I’ve found is a program called Text Wrangler made by Bare Bones Software, Inc.. This program will allow you to open any .plist file and edit it very easily. Some articles and websites recommend using this company’s BBEdit, which offers more powerful web authoring and administration tools. BBEdit is overkill for simply editing .plist files, especially since it costs $125 (or $49 for an educational license). Stick with Text Wrangler.
Usually, when you access the preferences window within an application, that program will write the changes to the .plist file associated with it. These are typically saved in the following location: ~/Library/Preferences
Editing the .plist file
The files are named something like com.apple.Safari.plist. This would be the file that controls the preferences that are set in Safari. The com.apple informs the user that the application is manufactured by Apple. Next, it tells the user the name of the program, Safari. When opened in a program like Text Wrangler, the data is easy to read and edit.
For most Mac users, there is never a time when they need to edit a .plist file. For those of us who like customizing our software with tweaks and hacks, there are instructions all over the web. One such website is macfixit.com, which features a few interesting .plist file modifications. Please take caution when editing these files - they are important. It might be a good idea to make a backup of the file and save it to a folder on the desktop before messing around with these files.