A thermal shirt is a type of clothing designed to provide warmth in cold weather. Made from materials like polyester or wool, these shirts trap body heat while allowing moisture to escape, keeping the wearer dry and comfortable. They are often used as base layers under other clothing, making them popular for outdoor activities such as hiking, skiing, or simply staying warm during winter. Thermal shirts come in various styles, including long-sleeve and short-sleeve options. They can be found in many brands, often marketed for both men and women. Some thermal shirts also feature additional elements like moisture-wicking technology or flatlock seams for added comfort and performance.