Google Chrome Plugins and Themes

When you click on the "Developer mode" option when on the Extensions tab you see three options. I know what the "Update extensions now" does, but what do the "Load unpacked extensions" and "Pack extensions" buttons do? I could not locate any info on them.

they are used to look at the code and create extensions respectively

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What version of Chrome are you running?

No, the load unpacked extension is used to run unpacked extensions (i.e. a folder with the source of the extension), useful for developers who want to test their extension without creating a package (i.e. a .crx file). The load extension button is for loading a .crx file already on your computer, just like what you do when you click a link to an extension online.