Faster fluorescence microscopy: advances in high speed biological imaging

•We describe recent advances in high speed fluorescence microscopy.•Modern microscopes are dividable into two classes — point-scanning and parallelized.•Advances in microscope technology are enabling improvements in imaging rate, spatial resolution and sample penetration.•Improvements in imaging rate often come at the expense of spatial resolution or sample penetration. The past decade has seen explosive growth in new high speed imaging methods. These can broadly be classified as either point-scanning (which offer better depth penetration) or parallelized systems (which offer higher speed). We discuss each class generally, and cover specific advances in diffraction-limited microscopes (laser-scanning confocal, spinning-disk, and light-sheet) and superresolution microscopes (single-molecule imaging, stimulated emission-depletion, and structured illumination). A theme of our review is that there is no free lunch: each technique has strengths and weaknesses, and an advance in speed usually comes at the expense of either spatial resolution or depth penetration.