The RK4 method, or Runge-Kutta 4th order, is a numerical technique used to solve ordinary differential equations. It provides an approximate solution by calculating the slope of the function at several points within each step, allowing for greater accuracy than simpler methods. In RK4, four calculations are made for each step, which helps to estimate the function's value more precisely. This method is widely used in various fields, including physics, engineering, and computer science, due to its balance between computational efficiency and accuracy.