Umbra refers to the darkest part of a shadow, where the light source is completely blocked. This term is commonly used in the context of eclipses, where the umbra is the area of total shadow cast by the Earth or the Moon. During a total solar eclipse, observers within the umbra experience complete darkness as the Moon obscures the Sun. In addition to its astronomical significance, the concept of umbra is also relevant in art and photography, where understanding light and shadow can enhance visual composition. The interplay of light and shadow creates depth and dimension, making umbra an essential element in these fields.