1) A container is an isolated guest in container-based virtualization. Container-based virtualization uses a single kernel to run multiple instances of an operating system. Each instance runs in a completely isolated environment, so there is no risk that one container can gain access to another’s files.
2) In Sun Microsystems' JavaBeans component architecture and in Microsoft's Component Object Model (COM), a container is an application program or subsystem in which the program building block known as a component is run. For example, a component - such as a button or other graphical user interface or a small calculator or database requestor - can be developed using JavaBeans that can run in Netscape containers such as browsers and in Microsoft containers such as Internet Explorer, Visual Basic, and Word.