What Is a Slot?
A slot is a narrow opening into which something can be fitted. The slit in the side of an airplane wing, for example, provides a flow path through the airfoil and helps it to produce lift. A slot also refers to a position in a group, series or sequence: She has a slot on the copy desk. It is also used in reference to a specific position, such as the mid-point of the (semi-circular) copy desk at a newspaper.
A slot is a container for content and can be used by the Render Scope to pass state to child components when rendering. In addition to being able to store and process data, slots can be used for layout purposes by providing an alternative to using the standard layout tags such as