Ever wanted to copy and paste text from a website without the need for its formatting, e.g. copying some colored text with large font from a website and pasting it inside your gmail account? If so, then this add-on is for you: https://addons.mozilla.org/en-US/firefox/addon/134

After installing and restarting your firefox, right-click on any selected text and choose “Copy as plain text” and then paste it anywhere.