A file manager is a computer application that provides access to files and helps perform common operation on them, such as copying, moving or deleting files. Although they are essential part of a computer system, and an operating system publisher usually supplies one or more file managers in a distribution of an operating system, a file manager is most often not a kernel-level tool but instead just an application. Many popular operating systems such as Microsoft Windows or UNIX systems in fact can use many different types of file managers, offered commercially by software publishers or freely by aspiring developers.
The first file managers were created for operating systems that were equipped with a text user interface. These file managers were typically represented computer disks, directory structures or network shares in their actual, physical layout, and allowed only a limited set of operation on these resources, such as moving or copying files from one directory to another, renaming files, or launching a program "associated" with a given file. With the advent and success of graphical user interfaces, file managers gained more functionality, such as the ability to associate files with the programs that created them, and operation via pointer devices instead of commands typed on keyboards. They also allowed a more intuitive way to place files and folders, and they made locating remote resources somewhat easier.
In the wake of the World Wide Web, file managers went through one more incarnation, and become completely independent of computer platforms or operating systems. A file manager software that is created to run from a browser does not require the installation of the software on the local machine, but it is automatically downloaded from a remote location - making access to the software virtually effortless and unrestricted. However, security concerns require that any file manager designed to run from a web browser be digitally signed, and obtaining a certificate to sign an application can be expensive.