A glass slide is a thin, flat piece of glass used primarily in laboratories for holding specimens for examination under a microscope. Typically measuring 75 mm by 25 mm, these slides provide a stable surface for samples, allowing scientists and researchers to observe microscopic details. Glass slides are often used in conjunction with coverslips, which are smaller pieces of glass that protect the specimen and prevent contamination. They are essential tools in various fields, including biology, medicine, and materials science, facilitating the study of cells, tissues, and other microscopic entities.