By using the right data type for a particular variable and understanding how to convert data types, you can write efficient code and reduce errors in your program.

Developers should have a basic proficiency of a language's data types. In this article, Irina Medvinskaya presents an overview of two types of predefined C# variables: value types and reference types.

JavaScript variables hold a wide variety of information and can be used with virtually any data type. Here's how to use variables to store numbers, text strings, objects, and more.

Classes as abstractions for sets of objects; class as an object factory; primitive data types, composite data types. Variable declarations for both types; difference between the two types.