A variable is a reassignable nickname given to a piece of information (i.e. words, numbers, etc.) that makes your code easier to read and maintain. Think about the following example. Imagine you are twelve and have an older brother who is four years older than you. When people ask you how old your brother is, you might say, “he is four years older than me”, or “he is sixteen years old”. Notice how the former is always true (your brother will always be four years older than you) and the latter becomes invalid immediately after your brother hosts his next birthday party. In this case, your age is a variable. It is reassigned, or changed, to a new number after every birthday but still holds the same meaning: your age. Everything else in relation to your age also gets updated automatically. To recap, a variable is often useful in describing relations. In the example above, your brother is always four years older than you rather than being at a specific constant age.

In C++, this is expressed as:

int myAge = 12;

int broAge = myAge + 4;

Wait a sec, what did you just write?

Good question! To initialize a variable in C++, you need to first tell C++ the type of information this variable needs to hold, give it a name, and set it equal to a value. If a value is not set, a newly initialized variable holds a default value of its type. In later topics, we will be able to come up with arbitrary types (i.e. Cat). For now, we will stick with predefined types of numbers.