When we write a code, we cannot write everything in plain English. We need to follow certain rules and format, so that the compiler can understand what we need to do in the program. Hence it has set some reserved words to identify the terms / actions that need to be performed. These reserved words are known as keywords. For example, when we say include, the compiler understands it as a preprocessor directive. Similarly when we write float flValue;, it understands that flValue is of float type and can store only real numbers. Here include and float is the keywords. In other words, we can say they are the short forms of the word or action. Whenever compiler finds those keywords, it evaluates them for its real meaning. Hence we need to be careful while using keywords. They need to be used at required place only and need not be confused or used as variables. There are many numbers of keywords that C supports. Some of them are :
As we can see above these keywords are used for declare a datatype for the variable, to control the flow of the program or to get the more information about the value in the variable.