A telescope is an instrument that is made to gather light.  The more light it gathers, the more powerful it is.

     When a telescope is sold by its magnification or power, they are cleverly avoiding the fact that it has no light gathering ability.  The power is meaningless.  The aperture or the size of the mirror is what the scope is all about.  

     The three most popular types of telescopes are Refractors, Newtonian Reflectors and Schmidt Cassagrains.

     Refractors use lenses to collect light.

     Newtonian Reflectors use mirrors to collect light.

     Schmidt Cassagrains and Maksutov Cassagrains use both mirrors and lenses to collect light.

     You can mount your telescope on one of two different kinds of bases.  A Dobsonian (uses Alt/Az) or an Equatorial (uses RA/Dec).

     A Dobsonian mount allows you to move the telescope by hand.  You can push, pull and swing it in any direction.

     An Equatorial mount tracks objects in the sky using worm gears and electric computerized motors.

     Like microscopes, telescopes use interchangeable eyepieces.  The magnification of an eyepiece changes what you see through the telescope.  The smaller the number, the closer you get.