Eyelash extensions are synthetic or natural fibers that are attached to individual natural eyelashes to enhance their length, thickness, and curl. They come in various materials, lengths, and styles, allowing for a customized look. The application process typically involves a trained technician using a special adhesive to bond the extensions to the natural lashes. The results can last several weeks, depending on the individual's natural lash growth cycle and maintenance. Regular touch-ups are recommended to replace any extensions that may have fallen out. Proper care, such as avoiding oil-based products, can help prolong the lifespan of the extensions.