Constants and variables should have a descriptive name. They should begin with a lowercase letter and be in CamelCase. The only exception is when the constant is global; in that case, the name of the constant should contain all uppercase characters with the words separated by underscores. I have seen numerous guides that frown upon having all uppercase names, but I personally like them for constants in the global scope because it stands out that they are globally, not locally, scoped. Here are some examples of proper and non-proper names:

//Proper Names 
playerName  
driveSize 
    
//Non-Proper Names 
PlayerName  //Starts with uppercase letter 
drive_size  //Has underscore in name