A computer works on a set of given instructions; it cannot differentiate between a number and a character. For example, if you write some numbers, such as 12345, and some character, abcsd, it cannot tell integers from characters. So, data types are used for this. The datatype tells which type of data is being used or referenced in a statement.

In all programming languages (C, C++, Java, JavaScript), data types are used. Every data type has a specific function of storing data. Many classical computer programming languages require you to specify the data type when you declare a data object. JavaScript does not have this requirement. Similarly, some databases require declaration of the data types for storing data.

JavaScript is a dynamic language. This means that if you declare an object, then its data type can be changed dynamically, for example:

var a=16;
a="abc";
a=true;

In the first statement, the data type is an integer; in the second statement, the data type is a character; and...