The endurance limit is the maximum stress level a material can withstand for an infinite number of loading cycles without failing. This concept is particularly important in materials like metals, which are often subjected to repeated stress in applications such as bridges and machinery. Below this limit, the material can endure cyclic loading without experiencing fatigue. Materials that do not exhibit a clear endurance limit, such as some alloys and polymers, may fail at lower stress levels over time. Understanding the endurance limit helps engineers design safer and more reliable structures by ensuring that materials can handle the expected loads throughout their lifespan.