Please tell me the difference between scope public,private,protected and when not written

The visible range of these four scopes is shown in the following table.

Description: If no access modifier was written above the decorated element, the friendly is represented.

Scope Current class same package descendant class other package

Public√√√√

Protected√√√x

Friendly√√xx

Private√xxx

Note: As long as you remember that there are 4 access rights, 4 access range, and then the full selection and the range in the horizontal and vertical direction of the order from small to large or from large to small, it is easy to draw the above diagram.

Please tell me the difference between scope public,private,protected and when not written