instrument for observing objects too small for the unaided eye
optical (light) microscope: magnification up to ~1500x, resolves to ~200 nm
electron microscope: transmission (TEM) and scanning (SEM), resolves to atomic scale
scanning probe: atomic force microscope (AFM), scanning tunneling microscope (STM)
fluorescence microscopy: labels specific molecules in living cells
revealed the cellular basis of life, bacteria, viruses, species microstructure
enabled semiconductor fabrication inspection and quality control
cryo-electron microscopy resolves protein structures without crystallization
complementary to telescope: one reaches inward, the other outward
essential for biology, materials science, and nanotechnology