A compound_microscope is a microscope with more than one lens. On a compound microscope, one lens is near the eye and is therefore termed the ocular lens. Other lenses are positioned on a rotating structure known as the nosepiece, which allows them to be moved in and out of viewing position. These lenses are termed objective lenses. Some compound microscopes have two oculars and are therefore called stereomicroscopes (binocular_microscopes).
Most of our microscopes have four objectives: low (4x), medium (100X), high dry (400X), and oil_immersion (1,000 with oil). When you look into an ocular, you will see a built-in pointer. If you are using a stereomicroscope, only one of the two oculars will have a pointer.
Some microscopes are used for viewing prepared microslides, but some (called dissecting_stereomicroscopes) are made for observing objects in a dish of water, or organisms that are being dissected.
Magnification is computed by multiplying the power of the ocular (usually 10x, but not always) times the power of the objective in use at the moment. Remember: "ocular times objective = magnification".
Remember to have the low power lens in position over the light opening in the stage when carrying, storing, or first using the microscope.