A squad automatic weapon (SAW), also known as a section automatic weapon or light support weapon (LSW), is a man-portable automatic firearm attached to infantry squads or sections as a source of rapid direct firepower. Weapons fulfilling this role can be light machine guns, or modified selective-fire rifles fitted with a heavier barrel, bipod and a belt/drum-fed design.

Squad automatic weapons usually fire the same cartridge (though heavier-bullet variants are preferred) as the assault rifles or battle rifles carried by other members of the unit. This reduces logistical requirements by making it only necessary to supply one type of service ammunition to a unit. These weapons are light enough to be carried and operated by one infantryman, unlike medium machine guns (such as the M1919 Browning) that require a crew to operate at full effectiveness; or heavy machine guns (such as the M2 Browning or the DShK) which fire more powerful cartridges but are also crew-served and typically also require a mounting platform to be operable.