Weber's Law is a principle in psychology that explains how we perceive changes in stimuli. It states that the smallest noticeable difference in a stimulus, known as the just noticeable difference (JND), is a constant proportion of the original stimulus. For example, if you are holding a weight of 100 grams, you might only notice an additional weight when it increases by 2 grams, which is 2% of the original weight. This law applies to various senses, including sight, hearing, and touch. It helps to understand why we may not notice small changes in our environment unless they are significant enough relative to what we are already experiencing.