What is the purpose and how does the static keyword work in programming languages?

In Java, the keyword static is used to indicate that a class member (variable or method) belongs to the class itself rather than to any specific instance of the class.

Main features of static:

• Static variables (fields): shared among all instances of the class, exist in a single copy.
• Static methods: can be called without creating an instance of the class, do not have access to non-static fields and methods.
• Static initialization blocks: executed when the class is loaded.

Example:

public class Counter {
    private static int count = 0;

    public Counter() {
        count++;
    }

    public static int getCount() {
        return count;
    }
}

// Usage:
Counter c1 = new Counter();
Counter c2 = new Counter();
System.out.println(Counter.getCount()); // Will output 2

Thus, static allows creating data and methods shared among all objects related to the class, not tied to a specific instance.