In C++, variables are containers for storing data values. To use a variable, you must declare its type and name, and optionally, initialize it with a value. Here’s how it’s done:

// Declaration without initialization

int age;

float height;

// Declaration with initialization

double pi = 3.14159;

char grade = ‘A’;

In the above examples, int, float, double, and char are data types, while age, height, pi, and grade are variable names. The equals sign (=) is used for initialization, where the value on the right is assigned to the variable on the left.