Listen we would all like to believe that our homes are burglar proof, but this is often very far from the truth. There are different types of burglar's out there - the ones that generally don't have any plan of action they will just go and kick in the door, and then there is the skilled professional that will creep in with tools that will allow themselves access quietly.
There are ways that you can protect your home or office building from the beginner to the professional. Most of which will begin with some small alterations to your door, and can be down without a large amount of money being put into it. You don't even really need to purchase a new lock, of course I would suggest replacing your lockset, or deadlock if it is a couple years old.
The first thing that you are going to need is to buy a box strike. A box strike is going to help improve the security of your lock. You will put this metal plate on the door jamb as well as into the locks bolt slides. These box strikes are not very expensive, and they are going to definitely increase the protection from a burglar gaining access to your property at least through the door.
This is a great way increase the security of your home. And you are able to achieve this even on a low budget. In order to increase the strength of your existing door lock you will need to take out the original short mounting screws and replacing them with one's that are much longer, such as with 3 inch screws. The short mounting screws are going to be on the door jamb not on the door itself. The reason why this is going to increase the security of the door is because the 3 inch screws that you are putting in are going to get screwed into the stud of the door, and make it much more difficult to break under the force of somebody kicking in the door.
These are the best ways to improve the security of your door. Of course you will find that there are many other ways that will make your home or office much more secure but it will require a bit more money to lie out. Such as upgrading your lock to a keyless entry, video surveillance, and many others.