The big question arising in the minds of the beginner would be, "What are functions?" and "Why are they necessary in any programming language?"

Functions are nothing but a small programming unit inside a big programming construct that generates a designated output. Let's try to understand with real-world scenario. It's difficult to think of a scenario where someone may not have access to television. What do you observe inside a normal television? On broader classification, considering a normal viewer, it has three functions:

• It has a display unit
• It has a volume control unit
• It has a channel tuning setup embedded inside the electronic circuitry

Although modern smart televisions have more complex functions, we will restrict our example to three main functions explained.

The display unit works differently from the other two functional units and its sole purpose is to put up a display to the user. Similarly, the volume control unit has its sole purpose to fine-tune the volume of the television, and, finally, channel tuning has the main function to have different channels loaded in the memory. Functions in programming language also work in a similar fashion, each has its own purpose defined. Some examples can be calculateMonthSalary(), calculateTotalBill(), and so on.

A method is an identical function in terms of name except that it is called on object and passed on the data, whereas a function is called directly by name and passed on the data to operate. A method is something that belongs to an object or in object-oriented programming class which contains the method. In this chapter, we will study more about functions.