In terms of memory and processing time, there's so little difference between $a and $a_variable_with_long_name that the time you've spent on this discussion is already greater than all the time you'll ever save if all your programs instantly rewrote to one-character variable names. However, there's a much bigger impact on typing time and code readability, and it's only this you should worry about. Variables should follow a standard naming system (regular variables all lowercase, constant variables all uppercase, underscores to separate words inside variable names - or whatever), there should be proper use of scope, and the actual length of each variable name depends entirely on your preferences. I prefer short variable names myself, whenever possible without compromising readability, and I rarely use a variable name longer than ten characters. I just dislike having my lines of code twice as long as they need to be.