Hi!
Data types are used to classify data that we manipulate in programs. Each variable we declare must be of a certain type. For eg., we have integers, characters, strings, real values (float) and so on. Based on the data type, the compiler allocates certain amount of memory to the variable.
Apart from these pre-defined data types, C allows us to define our own data types. We use "typedef" keyword for this. You can get more help from Turbo C / Borland C itself for each of the keywords.
If you want to know about "Data Structures" you may read the book by Tenenbaum or the one by Horowitz.
Hope this helps.
- Karthika