This document discusses various methods for counting bacteria, including direct microscopic counts, dilution series plating, membrane filtration, and electronic measurement. Direct microscopic counts can be done with stained smears under a microscope or using an electronic counting chamber. Dilution series involve making serial dilutions of a sample and plating them to obtain isolated colonies that can be counted. Membrane filtration uses filters of defined pore sizes to trap bacteria from a sample, which are then cultured and counted. Electronic methods measure turbidity from bacterial growth in broths or use cell counters with sensors to obtain cell counts.