Marines are the basic unit of Terran. Terran will build marines throughout the game (unless they go mech, but bio is the primary composition for all matchups).

Marines are the basic unit of Terran. Terran will build marines throughout the game (unless they go mech, but bio is the primary composition for all matchups). With upgrades marines have high dps & speed. They're a small unit which means you can fit more dps within a small area. They're ranged, unlike zerglings & zealots. Terran's drop ship, medivacs, can ferry around 8 marines while healing them on the ground In reality the counter to them is splash damage, though good micro can mitigate that somewhat, & Terran isn't going to stop building marines just because the opponent built some splash damage In some regards this can be rooted in people expecting StarCraft to be like Age of Empires, where as you climb the tech tree you discard previous tech. StarCraft instead prefers tech to fill out a composition & late tech often provides a support role to earlier tech https://tl.net/forum/starcraft-2/174912-the-problem-with-marines https://tl.net/forum/starcraft-2/174912-the-problem-with-mar... (2010)