Chances are when you use Whatsapp you probably think one tick means "sent" and another means "read." Nope! But now the app has been updated so that its read receipts are actually useful.
In fact, one tick used to mean "sent" but two just meant that it merely arrived at the other end — it had nothing to do with whether it had been seen or not. Now, Whatsapp make the two ticks change colour to let you know that your recipient has read your wise words. Whatsapp explains in its newly updated FAQs:
Obsessing over a lack of reply just got a whole lot easier. [Whatsapp]