Binary code is a number based system using just two digits, 0 and 1. When a user views an IP address it is generally displayed in decimal code to make it easier to understand. Decimal code consists of 10 digits, which are 0-9.
An IP address consists of four groups of eight numbers. Each of these groups can be used, not just as a simple address, but also to signify a particular group. These can be known as classes. For example for a particular business, where there would be various computers under a single network, a class would be used to show they are all part of the same group.
Each group of eight digits in an IP address is called an octet. These are split into two sections: The net and the host. The net octet could be a shared class, as I explained, within a particular business.
The host signifies the particular computer within the network. There are several particular classes with their own functions. For example there is Class A, which is used by large multi-national companies, which would have networks spanning more than one country. These would have a specific code. Class B would be used for medium networks, for example a network in a school or college. Class C would be for small or medium sized businesses. There are various other classes, but these are perhaps the most common.