Convolution is a mathematical operation used to combine two functions to produce a third function. It is commonly applied in fields like signal processing and image processing to filter signals or images. The process involves sliding one function over another and calculating the area of overlap at each position, which helps in extracting important features. In practical terms, convolution can enhance or detect patterns within data. For example, in neural networks, convolutional layers are used to identify features in images, such as edges or textures, by applying filters. This allows machines to recognize objects and make decisions based on visual input.