Flow cytometry (FACS) and magnetic activated cell sorting (MACS) are techniques used to analyze and separate cells based on their physical and chemical characteristics. FACS uses lasers to detect cell properties and sort cells into containers one by one, while MACS uses magnetic microbeads attached to cells to separate them in high gradient magnetic fields. These techniques have various applications in research including identifying stem cells, characterizing cancer cells, studying cell cycles, and isolating cell populations for further analysis.