What Is Global Variable?

Global variables are like the annoying cousin who shows up at every gathering, except they're a programming language construct. They're declared outside any function and are accessible to all parts throughout the program. Global variables can be accessed from any function in the program since they are displayed outside of any function. A global state or global environment is a group of global variables that, when combined, describe various aspects of the program or environment in which the program runs. Global variables are usually declared on top of all functions. They are kept to a minimum, as all functions can manipulate them during the program's run time, which is considered dangerous by most programmers because they may accidentally be changed, resulting in bugs. Global variables are like a party guest that won't leave. They're everywhere; they know everyone and won't go home. In programming language terms, global variables are accessible everywhere in a program. Any function can change them at any point and may impact the program. Global variables were used heavily in early computer programming, where memory was minimal. Because of this, it was easy for programmers to lose track of their values and hard to keep track of where they had changed or why they were changed. To make things worse, global variables took up valuable memory space, which meant less room for other essential parts of the program—like functions! Source code is best understood when the scope of its elements is limited, so because of their non-locality, it is hard to keep track of where they have been changed or why they were changed. Global variables are like a gift to your code. You don't have to ask for them or even buy them—they're just there, waiting for you to take them and use them at will. Imagine if every time you wanted a global variable, you had to go through the hassle of filling out an application and taking a tour of the office so they could decide if they'd give you a pass. That'd be CRAZY!