First, identify the kind of module your system uses by the form factor (the physical form of the module — generally, desktops use UDIMMs, laptops use SODIMMs), then figure out the memory technology ( DDR5, DDR4, DDR3, etc.) your system supports.
Choosing the best RAM for your system involves two things: compatibility and how much RAM your system can support. First, identify the kind of module your system uses by the form factor (the physical form of the module — generally, desktops use UDIMMs, laptops use SODIMMs), then figure out the memory technology ( DDR5, DDR4, DDR3, etc.) your system supports.