Screensavers are a standard feature on most Macs and PCs that compel the display to loop a constant motion graphic to mitigate the effects of screen burn-in. The need for screensavers isn’t as great on mobile handsets like smartphones and tablets however, since the display typically turns off automatically when it isn’t in use to preserve battery life – a constraint that wired Macs and PCs don’t need to worry about.
While you don’t really need a screensaver on your smartphone or tablet, that doesn’t mean you can’t have one regardless. Apple doesn’t allow this on their brand of mobile handsets out of the box, but if you’re jailbroken, then you can take advantage of a newly released jailbreak tweak dubbed SleepSaver by iOS developer iCraze to circumvent this restriction.