Widgets are the pluggable user interface components that you use to define the functionality of your spaces. Widgets communicate with other widgets by publishing and handling events.
By itself, a widget typically has limited or specific capabilities. However, you can combine widgets to interact with each other to perform related tasks. Combined widgets are called a mashup. For example, you can have a widget that displays news items from an RSS feed and another widget that you can use to create tasks that you assign to someone. If you combine the two widgets onto one page, you have created a mashup in which you can see a news event and react to it by assigning someone to investigate whether the event might affect your business.