A class with default access has no modifier preceding it in the declaration.
The default access is a package-level access, because a class with default access can be seen only by classes within the same package.
If a class has default access, a class in another package won’t be able to create a instance of that class, or even declare a variable or return type. The compiler will complain. For example:
package humanity;
class Person {}
package family;
import humanity.Person;
class Child extends Person {}
Try to compile this 2 sources. As you can see, they are in different packages, and the compilation will fail.