Mercury (the planet of communications, travel and commerce) starts moving retrograde today (April 17th) through May 11th.   This means that Mercury is not at full power and can cause delays or misunderstandings in the topics it rules.  For example, delivery of packages could get delayed, travel may be problematic (leave extra time and have patience) and emails messages could be sent to the wrong person.
It is in the sign of Taurus, which means that purchases shouldn't be made without knowing in detail the return policy.  Also, don't decide to do any makeover right now - you might regret it. 
Mercury Retrograde does help you to go within and review your own communication style.  How do you speak, write, express yourself?  This is the best time to look at that and develop changes.
Out of all the planets, we seem to notice Mercury Retrograde the most because our society is so plugged into communications and travel.   If we can't physically travel, we cyber travel.  So make sure to back up your computer, keep copies of important files, get an oil change sooner than later, test equipment before use...well, you understand what I mean.  The mantra from April 17th through May 11th - do your best to plan for the unexpected.
If your Mercury is Retrograde in your own Natal Chart, this will not affect you as much.  If you're not sure, get a copy of your chart and you'll be able to tell if you Mercury was Retrograde when you were born.  You're one of the 18% of the population that actually is not affected by the four times a year Mercury goes Retrograde.  Many would consider you lucky!