The fundamental component of GStreamer is the "element", an object that
sources and/or sinks data.  Elements are connected to each other via
"pads", which are extremely light-weight generic connections.  Elements
can be contained inside "bins", which themselves are elements.

A pipeline consists of any number of elements, connected to each other one
after another.  A source would connect to one end of a decoder, which in
turn would be connected (on the other end) to a sink, such as a sound
card.  Other elements can be located anywhere in the pipeline, including
tees and transcoders.