The gettext filter gives us a really easy way to change text anywhere in our WordPress install, including plugins and themes, without ever changing any of the original code. It is a great way to easily customize labels, headings, button text, and any other text we wish to change.
Like most filters in WordPress, the gettext filter is exceptionally simple to use, and the main purpose of this filter is to allow us to change text in WordPress core, WordPress plugins, and WordPress themes.
For example, let’s say a plugin has a button that says “Add to Cart”, but you would rather it say “Purchase”; the gettext filter will make changing this button label super simple. This example assumes that the plugin does not already have a method for changing the label.
A very important thing to note about the gettext filter, however, is that it only works for text strings that are localized and ready for translation.
Note, as pointed out by Otto, you should take care when using the gettext filter, as it runs on every single string in WordPress core.
Have you ever used the gettext filter before? have problems with it? Found it to be awesome, or terribly confusing? Let me and everyone else know in the comments.