Web browsers don't come with options to highlight text on web pages, at least not in their default state.
This may sometimes be necessary or desired, for instance when you use a resource regularly and want to make sure that the most important information are highlighted for better accessibility.
With Textmarker for Firefox, things could not be easier. To highlight text simple select it using mouse or keyboard, and hit m afterwards to use the first configured color for the highlighting.
You may hit 2 or 3 instead to mark with different colors instead, and if you don't like the default color scheme for a shortcut, you may modify it in the options.
There you may modify the background color but also other parameters such as formatting options, a different text color or size and font.
Textmarker adds an entry to the context menu of the mouse which you may use instead to highlight text on pages you visit in Firefox.
Changes are temporary by default but can be made permanent with a tap on Ctrl-Shift-S. If you think that this is too much work, you may change this directly in the options so that all changes are saved automatically and persist across sessions.
The control options page provides you with options to enable or disable select features. You may disable mouse support there for instance, or disable one of the markers or other functionality that you don't require.
As you can see on the screenshot above, additional shortcuts are provided, for instance to undo the last action or to use the built-in Wikipedia look up option which opens the term you have highlighted on Wikipedia in a new tab in the browser.
Another interesting feature is the extension's built-in bookmarking functionality which scrolls the text automatically to the lowermost bookmark on consecutive visits. This can be useful if you are reading a book online or access a large text on a site that you cannot read in a single session.
Closing Words
Textmarker is a useful add-on for Firefox that adds text highlighting to the browser. While that would be great itself, its the extra features like bookmarking or permanent highlighting that make it shine.
Source: http://www.ghacks.net/2015/07/27/textmarker-mark-text-temporarily-or-permanently-in-firefox/
