In Java, a package is a namespace that organizes classes and interfaces into a single unit. Packages provide a way to encapsulate and reuse code, making it easier to maintain and update large projects.

A package can contain any number of classes and interfaces, and a class can belong to only one package. By convention, package names are written in lowercase and use reverse domain notation, such as

com.example

To use a class from a package in your code, you first need to import it. For example, if you want to use the Scanner class from the java.util package, you would write the following import statement at the top of your code:

import java.util.Scanner;

You can also import multiple classes from the same package using a wildcard:

import java.util.*;

This would import all classes from the java.util package.

By organizing your code into packages, you can avoid naming conflicts, make it easier to navigate your code, and enforce a clear structure to your project. Additionally, Java provides several built-in packages, such as the java.util and java.io packages, that provide a wide range of functionality, making it easier to write complex applications.