Security -or- do I really need a VPN

[Shinyshiny]

I realize this is really old but I was attempting to understand VPNs a week or two ago and I'm really not sure I'm getting it at all.

I use Chrome and I downloaded and extension for it but I don't know if that's something that automatically starts when I log in or if I have to do something to enable it.

Also, with my phone and tablet they seem to have an option for VPN but I don't know how that works either. If this is too much to explain don't worry about it. If you can just answer about the extension that would be really helpful.

One of my problems with my memory now is following instructions so, though I am smart enough, it gets jumbled and I give up because I'm overwhelmed.