Amateur astronomy, also called backyard astronomy, is a hobby whose participants enjoy watching the night sky (and the day sky too, for sunspots, eclipses, etc.), and the plethora of objects found in it, mainly with portable telescopes and binoculars. Even though scientific research is not their main goal, many amateur astronomers make a contribution to astronomy by monitoring variable stars, and discovering transient objects, such as comets.
Large encounters of amateur astronomers in dark places suitable for sky viewing are called star parties.
Some good books for amateur astronomers to start with:
The Stars, a New Way to See Them -- H.A.Rey