In Java, a package is a namespace that organizes a set of related classes and interfaces. Packages provide a way to group related classes and interfaces and prevent name conflicts between classes with the same name.

Java has a built-in package system, and all classes in Java are part of a package. If you do not specify a package for a class, it will be part of the default package, which has no name.

To create a package, you use the package keyword followed by the name of the package at the top of your Java source file. For example:

package com.example;

public class MyClass {
  // class implementation goes here
}

In this example, the MyClass class is part of the com.example package.

To use a class from a package in your code, you can either use the fully qualified name of the class (including the package name), or you can import the class using the import keyword. For example:

// Using the fully qualified name
com.example.MyClass myObject = new com.example.MyClass();

// Importing the class
import com.example.MyClass;

MyClass myObject = new MyClass();

Packages are useful for organizing your code and preventing naming conflicts between classes. They also allow you to create reusable libraries of code that can be used in multiple projects.