A logarithmic function is the inverse of an exponential function. It helps to determine the power to which a base number must be raised to obtain a certain value. For example, in the function y = \log_b(x), b is the base, x is the value, and y is the logarithm. Common bases include 10 (common logarithm) and e (natural logarithm). Logarithmic functions are useful in various fields, including science, engineering, and finance. They can simplify complex calculations, especially when dealing with large numbers. The graph of a logarithmic function increases slowly and never touches the x-axis, indicating that it approaches zero but never reaches it.