A variable must be ____________ before it can be used in a program.

Understanding the concept of variable declaration is fundamental in any programming language, including C++. When we declare a variable, we essentially tell the compiler about the existence of the variable and the type of data it will hold. Variable declaration also includes giving the variable a unique name that adheres to the naming conventions of the language.

In C++, you typically declare a variable with a syntax that includes the data type followed by the variable name. For example, declaring an integer variable named 'score' would look like this:
int score;
Following the declaration, the variable 'score' can be used within the scope it is declared to store integer values.

The cornerstone of programming includes understanding the basics like data types, variables, operators, control structures, and syntax. Starting with the essentials, a data type defines the type of data a variable can hold, such as integers, floats, characters, or booleans.

Once a variable is declared, you can perform operations on it using operators, which can be arithmetic (+, -, *, /) or logical (&&, ||, !). Control structures such as 'if' statements, loops ('for', 'while'), and 'switch' cases allow you to control the flow of the program based on conditions and repetitions. Together, these basics form the foundation upon which more complex programming principles are built.

C++ is a versatile object-oriented programming language used for various software development tasks. This language offers a blend of both high-level and low-level programming features. In C++, in addition to variable declaration, you have to be familiar with the idea of variable initialization, which is assigning a value to a variable at the time of declaration. For example:
int age = 25;
This not only tells the compiler that 'age' is an integer variable but also initializes it with the value 25. Initialization can help reduce errors and make the code more readable by providing initial state for variables.

C++ also supports classes and objects, which allow for encapsulation, inheritance, and polymorphism. These features enable developers to create complex programs with reusable and maintainable code. Knowing how to declare and initialize variables is just the starting point in the expansive world of C++ programming.