Object Orientated programming or OOP is a special way of developing computer programs. When programming languages were first developed they were procedural, that is the lines of code would be executed one after another until the program was completed. Many languages such as C and BASIC are still procedural based.
Object orientation takes a different view of the world. Object orientated programs try to model the world and break it down into small components. An example would be a PC, the PC has components such as a CPU, Motherboard, Graphics card, Mouse etc, each of which can be considered as an object. By connecting all these things we can create a complete computer.
OOP takes a similar approach. It will develop individual components that can be put together in order to build something new. Once a component has been developed, it may be reused in another application. In the same way that you can unplug a graphics card from one PC and plug it into another. This concept of reuse is central to the idea of OOP.