Refractor:
A refracting telescope (refractor), the first kind of telescope invented, uses a large lens to collect and focus the light into an eyepiece.

Newtonian:
The reflecting telescope (reflector), was invented by Issac Newton in the 1660s. It uses a large mirror to collect and focus the light into an eyepiece or secondary mirror.

Hubble:
The Hubble Space Telescope observe planets, stars, galaxies and nebulas in visible light as well as near UV and near infrared.

Spitzer:
The Spitzer Space Telescope observe galaxies, infant stars and newly forming planetary system in infrared.  

Chandra:
Chandra X-ray Observatory enables exploration of high-energy phenomena like black holes, neutron stars, and supernovas.

Radio:
Radio telescopes are used to study radio emissions from stars, galaxies, quasars, and other astronomical objects.