Reflecting / Dobsonian Telescopes
Also called Newtonians, reflecting scopes are the best bang for the buck. They have fat tubes with a parabolic mirror at the bottom. Light from the sky enters the tube and gets reflected by this mirror back up to the top of the tube where there is a small diagonal mirror that bounces the light out the side of the tube to your eye.
A Dobsonian telescope is an alt-azimuth mounted Newtonian telescope design popularized by the amateur astronomer John Dobson starting in the 1960s. Dobson's telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low-cost telescope. The design is optimized for visually observing faint deep sky objects such as nebulae. This type of observation requires a large objective diameter (i.e. light-gathering power) of relatively short focal length and portability for travel to relatively less light polluted locations.