Do you see that white vertical line on the roads each time you go out? Well they are meant for something. They are guides and are there to also tell us to stick to our lane. Unlike in most countries where drivers have a tendency to shift lanes and even disregard these lines, they are really meant to guide you to stay in your lane for a more orderly way of driving.
They are also used to make sure that traffic is manageable at times. A road is usually made for 2 vehicles while highways go up to at most 4 lanes. Just imagine a major road without these lines and many vehicles driving simultaneously. You can just imagine the traffic it can cause due to uneven distribution of driving space thanks to lack of discipline and road ethics.
These are normally taught to you when you study driving. They are the basic yet important issues. In some countries, if you do not follow these simple rules, chances are you are dangling for a traffic violation ticket. Violations and fines for obstruction or even reckless driving can be charged on you and these cost heavy fines and a lot of discomfort for you. And in some countries, it goes as far as taking your license and being a cause for concern when it is time for you to renew them.
You can avoid troubles when you drive. Driving is easy if you do it the right way. Just review what they taught you in driving school and you will be fine.