Essential OOP Keywords: static, final, super, this, volatile, transient & assert

• Static Variable: Class-level variable stored in static memory. Shared across all instances.

• Static Method: Belongs to the class, not an object. Can be invoked directly as `ClassName.method()`. Cannot access non-static instance fields or use `this`.

• Static Block (Tricky Question 16): `static { ... }` block executed once when the class is first loaded into memory by the classloader, prior to any constructors running.

• this: Refers to the current instance of the class. Disambiguates instance variables from parameter variables with identical names (`this.age = age`).

• super: Refers to the immediate parent class object. Used to invoke parent constructors (`super(...)`) or overridden parent methods (`super.render()`).

Tricky Question 8: The `final` keyword serves three distinct enforcement roles:

• final variable: Makes the value constant; cannot be modified once initialized.

• final method: Prevents method overriding in any subclasses.

• final class: Prevents inheritance entirely (no class can extend it, e.g. `java.lang.String`).

• volatile (Tricky Question 23): Ensures that a variable’s value is always read from and written directly to main RAM, bypassing CPU local L1/L2 caches. Essential for thread visibility without locking overhead.

• transient (Tricky Question 25): Instructs the serialization engine NOT to serialize this variable into a byte stream. Useful for passwords or temporary runtime handles.

• assert (Tricky Question 36): Used for internal testing and debugging to verify invariants (`assert x > 0 : "Invalid";`). Throws `AssertionError` if false.

• var (Tricky Question 38): Enables local variable type inference in modern Java 10+, allowing the compiler to deduce the variable type based on the assigned expression.