A Fourier transform is a mathematical technique that transforms a function or signal from its original domain, often time or space, into a representation in the frequency domain. This allows us to analyze the different frequency components that make up the signal, making it easier to understand and manipulate. In practical applications, Fourier transforms are widely used in fields such as signal processing, image analysis, and communications. They help in tasks like filtering noise from signals, compressing images, and analyzing sound waves, providing valuable insights into the underlying patterns and structures of data.