What does static mean for variables and methods?

static members

static belongs to the class, not each instance—one copy shared by all objects. Static methods cannot access instance fields directly.

• static fields: counters, caches, constants (with care for thread safety).
• static methods: utilities (Math.max)—no this.
• Static blocks run once when class loads.

class IdGenerator {
  private static int next = 1;
  static int nextId() { return next++; }
}