A plugin is a software add-on that is installed on a program, enhancing its capabilities. For example, if you wanted to watch a video on a website, you may need a plugin to do so. If the plugin is not installed, your browser will not understand how to play the video.
Where can I get plugins for my browser?
Every web browser has an official website where you can download and install plugins (also called "add-ons" or "extensions"). The web browser publisher (e.g., Google, Mozilla, Apple, etc.) verifies the plugins are not harmful before making them available to download.
You should always install plugins directly from the browser's official website.
Because the Vivaldi and Brave browsers are based on Chromium, they also use Chrome extensions. Download extensions for these browsers from the Chrome Web Store.
Should I use "plugin" or "plug-in" in my writing?
Today, both versions of these words are correct. Technically speaking, "plug-in" (with the hyphen) is the correct way to write this word and it's also in the Microsoft Manual of Style as "plug-in." However, "plugin" is the most widely used version of this word and most people and companies have opted for the non-hyphenated version of this word.