Computer graphics uses three different types of algorithms to generate lines namely: 1) DDA Line drawing algorithm 2) Bresenham Line drawing algorithm 3) Mid Point Line drawing algorithm This video focus on DDA Line drawing algorithm. It is an incremental method of scan conversion of line. In this method calculation is performed at each step but by using results of previous steps. It is a faster method than method of using direct use of line equation. 

DDA Line Algorithm: https://www.geeksforgeeks.org/dda-line-generation-algorithm-computer-graphics/ 

Difference between DDA & Bresenham's: https://www.geeksforgeeks.org/comparions-between-dda-and-bresenham-line-drawing-algorithm/