Q.What are access specifiers in Java? Name the four levels and state, for each, from where a member can be accessed.

Access specifiers decide which parts of a program may use a class member, ranging from fully open to fully hidden.

Meaning. An access specifier (or access modifier) is a keyword written before a field, method or class that controls which parts of the program are allowed to access it. Java provides four levels, from most open to most restricted.

The four levels:

• public is the least restrictive — a public method can be called from anywhere.
• private is the most restrictive — a private field is invisible outside its own class, which is exactly what we want for hidden data.
• protected sits in between and is important for inheritance: a subclass can use a protected member of its parent.
• default (also called package-private) is what you get when you write no specifier at all.

Why they matter. By choosing the right specifier we expose only what the outside world should use (usually public methods) and hide the internal data (usually private fields) — the basis of encapsulation.

Thinking 'no keyword' means public — it actually means default (package-private), which is more restrictive. Also confusing protected with public; protected still hides the member from unrelated classes in other packages.