The basics: A retrograde occurs when a planet appears to be moving backwards from our vantage point here on Earth. It isn't actually moving backwards, it just appears that way. Mercury turns retrograde most often because it's nearest to us, about 3-4 times per year, and lasts for several weeks. When a planet retrogrades, what that planet rules tends to be thrown off, along with what the sign it's retrograding in rules.
With Mercury retrograde, we experience a shadow and a storm. The shadow period starts when Mercury first hits the point in the zodiac it will turn direct at, and ends when it last hits the point in the zodiac it will turn retrograde at. Most people don't feel the effects of Mercury retrograde until it enters the storm period though. The storm period of Mercury retrograde is when Mercury is moving at its slowest, less than 40 minutes per day. Mercury is a fast-moving planet and hates it when he's moving slowly. There's usually two storm periods, one around the time Mercury turns retrograde, and one around when it turns direct.
The shadow of this Mercury retrograde begins January 5th and ends March 3rd. The exact retrograde begins January 21st at 10:54AM ET and ends February 11th at 9:57AM ET. The first storm period is January 18th - 25th, and the second storm period is February 7th - 18th.
This Mercury retrograde occurs entirely in air sign Aquarius, which rules friendships, groups, charity, humanitarianism, the future, the internet, and our hopes, dreams, and wishes for our lives. So all of that is screwed! LOL We can be too optimistic or pessimistic, looking toward the future and thinking everything is going to go to hell in a handbasket, or being delusional and thinking things will work out fine when they're falling apart right in front of us. We can find it hard to hope, to dream, and second-guess the dreams we have for ourselves, our communities, our countries. This is made worse by the fact that we're bickering with the people that are supposed to be our friends, having a hard time getting along with anyone, even pretending to. We can see countries back at war with one another again that had called a truce, or countries at war take a step back for a moment.
Groups can be a problem, those we belong to, and those that congregate for one reason or another. Whenever we see problems come about, it may stem from a group more often than not. Crowds = problem. We have a hard time reaching out and helping the world on a grand scale, not wanting to or experiencing complications, or we have to help in ways that we did before and didn't think we'd have to again. We have a hard time grasping things on a large scale, and looking at the world with more objective eyes.
And the internet, the thing that our whole world hinges on now. We have more problems accessing it, we hear/see more about it being restricted in some places or to some people, it's used against people/countries, or some sort of internet scandal breaks out. No matter what, back up your important files, and wipe out anything incriminating!
The Mercury retrogrades this year will occur in the air signs, which are social signs, so we can find that in general, we have a harder time getting along, being sociable, and relating to one another. These are also the signs of the mind, so Mercury retrograde will screw up our communications even more this year.
This Mercury retrograde makes two positive major aspects while in retrograde, a sextile to transit Uranus on January 28th, and a sextile to transit Saturn on February 5th. We can adjust easier to the changes being made with Uranus, and try to wrangle them, getting them under control with Saturn. One thing to note is that the end of this Mercury retrograde will be square (hard aspect) the solar eclipse of October 23rd 2014, so we could see some difficulties associated with things that came about from that eclipse at the end of the retrograde.
The turn retrograde begins at 17 degrees Aquarius, so those of you Aquarians born February 6th - 8th may feel the turn retrograde most. The turn direct occurs at 1 degree Aquarius, so those of you Aquarians born January 23rd and earlier may feel the turn direct most.
For the rest of you, check the house(s) Mercury will be retrograding in of your own natal chart, and any aspects Mercury will make during its retrograde to your natal planets, to fully understand how it will impact you personally.
If you have Mercury retrograde in your natal or progressed chart, you may not feel the worst of this. Those individuals generally don't experience the difficulties of the retrograde because it feels more natural to them. Of course, chances are everyone else around them doesn't have the same aspect, so they can still experience difficulties brought on by others.