As you use iOS, you’ll find that Apple loves to use Blue as the system’s natural tint color. You’ll find this blue tint across various UI elements, including, but not limited to: iMessage chat bubbles, links, loading bars, and even those shortcuts that appear at the top right of the interface as you navigate preference panes in the Settings app.
Blue is a cool color, but if you’d rather have more control over your handset’s tint color, then we’d suggest turning your attention to a newly-released jailbreak tweak called Rainbow by iOS developer Justin Proulx, as it lets you change this color to almost anything you could ever want.