Definition can be either implicit or explicit 𝑦𝑘+1=𝑦𝑘+∫𝑡𝑘+1𝑡𝑘𝑓(𝑡,𝑦)𝑑𝑡 explicit RK4 the most common Runge-Kutta scheme, 4-th order 𝑦𝑘+1=𝑦𝑘+ℎ𝑘6(𝑘1+𝑘2+𝑘3+𝑘4)