Traditionally, multi-tasking was mostly associated with the many roles that housewives had to take on; watching the news while smoking a cigarette and vacuuming the house, or ironing clothes while monitoring the children’s homework. Today, with our excessive use of social media, multi-tasking almost comes naturally to all of us. It is very easy to speak on the phone while responding to emails, and maybe even skimming through the news as well. We can actually have dinner with one group of friends while engaging with another group over social media. The easiness with which we do this however can only be limited to media and communication. 
When we are looking to multi-task in more important areas, such as work or academia, it ends up hindering our productivity instead of improving it. So we might think that we are saving time by doing two or more things at once, but we are actually doing them with less precision, therefore compromising our effectiveness. Studies have shown that doing things at the same time means we are doing them with less intensity and less focus. When we jeopardize the quality of our performance, we fail at actually completing any tasks. 
Moreover, research suggests that with time, people who multi-task become slower at shifting their attention from one task and onto another. Multi-taskers are also more easily distracted by things on the side as they become accustomed to dividing their attention. Focusing on one thing becomes increasingly difficult and they are less able to switch their attention from one thing to another efficiently. In addition to that, doing more than one thing at once creates more stress and hinders productivity even further. 
Despite the difficulties, we are still able to walk and talk, or walk and drive at the same time without having to think about it. This means that we are able to do things simultaneously without trouble when they are not closely related and are performed by different parts of the brain. Checking e-mails while also reading would constitute difficult tasks then, being that they are similar in nature. It is interesting to note as well that a study conducted at the Stockholm University found that sometimes men are the ones better at multi-tasking, and this difference in performance was attributed to female menstruation.