Question: What is the real world?
I find this to be an interesting question, because the mere asking of such encourages the notion of their being multiple worlds. But what is a world? Is it a planet, or a dimension? Or maybe merely a world which you merely perceive?
Most of us have seen the Matrix, which gives some interesting doubt as to the legitimacy of the world which holds this text that you are reading. Less of us have seen the Thirteenth Floor, which gives another interesting outlook and I recommend watching.
I tend to cling towards the more psychological definition of a world. Even without definitive proof of multiple worlds, universes, or planets with life, multiple worlds are at play in most people's lives, today. I lay claim that a world is a reality which you perceive around yourself that is relatively separate to the rest. It generally has no correlation with the other world(s), but can have some form of connection depending upon the circumstances.
Most worlds fulfill the cycle of human needs, such as a work, reward, achievement cycle. Others are purely for pleasure. I believe that the mind is mostly linear, and one-tracked. You are more in the same world if everything flows in harmony. Multiple worlds involve abrupt changes between thoughts and realities.
The most common other worlds today involve the Internet. Maybe an MMORPG such as World of Warcraft, or Facebook. Some people come to these worlds to fill a void in the world they spend the most time in. If they long for attention and friendship and are shy, Facebook and Twitter make for a simple and fast illusion of such with less to lose. The belief that in the same digital world on the other end of the wire, a real and dynamic human being is giving them attention, is generally what keeps them going.
Or sometimes, it's not a lack that encourages delving into the other worlds, but an excess. Of stress, trauma, or simply a lifestyle which they do not want. The other world is an escape, where they forget about work. They have friends they actually care about, and someone who really listens to them. Or perhaps, that is also a lack, but I trust you are following my logic.
But, you do not need digital boundaries to form other worlds. Though they can also be had with phones and a gripping TV show which you try to connect into, they are also readily formed in real life. The world of reality has most parts interconnected. Your world is formed by the people you talk with, the job you work, and how you relax. An extreme of emotion, distance, or difference in lifestyle will form another world. Someone you really love and care for, is another world for you. Just you and them are in the world, or at least that is your hope. Or even alone, at night you may be a drug runner or do something which involves no one else knowing of your other identity. Other worlds are conversations with people that you don't have in the main world. Something may entice you so much, yet you never get the chance to indulge in deep conversation over it. The one person who you can talk with it over, forms another world which the other members of your normal world are not connected to.
These worlds are effectively separate mental states. If the mind is one-tracked as I say, the majority of the mind is only involved in one world at a time. Or, it can split and be in more than one at once, but it consumes each as a whole reality at the same time. You can feel two things at once when you act in these separate realities, taking from both the things you need and desire.
My personal belief is that these multiple worlds are dangerous to the mind. I believe a life closest to present-tense thought with minimal separation is best. Although not all additional worlds are bad, if you long for things in another world, especially a digital world, I believe you should take what you want in the digital realm and insert it into reality. It's better to improve upon real life rather than joining in on the general fakeness of a digital life to satisfy something you are generally too afraid to make a reality in your real life.
In summation, the real world is the world which you have the greatest propensity and bias towards, times the time you spend in it. The world real is merely an illusion which you choose to accept.