Starbucks has been highly successful in expanding its coffee chain across the US and world through aggressive growth strategies. However, it now faces increased competition from other chains like Dunkin' Donuts, McDonald's, and Caribou Coffee who are targeting the coffee market. These competitors have launched advertising campaigns and promotional tactics directly taking aim at Starbucks to gain market share in the retail coffee space. Starbucks remains the leading chain but must continue adapting to changing consumer preferences and competitive threats to maintain its success.