I have recently started learning PHP and have been working on a small project. I noticed that sometimes when coding, I accidentally use different cases for my variables. For example, I would write '$myVariable' in one part of the code and '$myvariable' in another. This got me wondering, are variables case-sensitive in PHP? I'm not really sure if it would cause any issues or if PHP treats them as separate variables altogether. Could someone please clarify this for me?