Imagine this scenario: you have an old Android smartphone. Its primary function has long been lost—perhaps the screen is cracked, the mobile communication module has died, or the phone has simply become obsolete. There’s not much point in selling it for next to nothing, but you could definitely put it on “permanent charge” and set it up as a server. You won’t even need to run Linux on the smartphone or compile anything. Everything you need is available on Google Play.