Currently, I am a freshman in High School and I do frontend development and user interface design (HTML, CSS, PS)<p>I am looking to learn about backend programming over the summer. I currently have a working knowledge of Java (1yr), and basic knowledge of Javascript.<p>I'm debating over learning Ruby, Python, Javascript (Node.js), or PHP.<p>My goal is the ability to build web applications, such as a content management system, todo list, etc.<p>Can I have some suggestions on what to learn? I'll have about 3 months to gain knowledge on the language.<p>Thanks :)