Java Packages Explained: How Namespaces Keep Large Codebases Organised

Java packages are namespace mechanisms that group related classes, interfaces, and enums into a folder-like structure, preventing naming collisions and improving code organisation. Without packages, two classes sharing the same name — whether written by the developer or imported from a library — would cause compiler conflicts, while packages allow both to coexist under distinct identifiers. Packages also enable package-private access control, letting developers hide implementation details from outside code while keeping them visible to related classes within the same package. Java convention recommends using reverse domain names in all lowercase for package naming, such as com.example.billing, with each dot corresponding to a physical directory on disk. Placing classes in the default package — what Java assigns when no package is declared — is discouraged for real applications, as such classes cannot be imported by classes residing in named packages.