Warmers are activities or exercises used at the beginning of a lesson to engage students and prepare them for learning. They can include games, discussions, or quick tasks that activate prior knowledge and stimulate interest in the topic. Warmers help create a positive classroom atmosphere and encourage participation. These activities are commonly used in language teaching, such as in ESL (English as a Second Language) classes, to break the ice and build rapport among students. By incorporating warmers, teachers can enhance motivation and set a productive tone for the rest of the lesson.