In the modern day we have all our HD TV’s, but do we really understand what the i’s and p’s mean? after 1080 and 720 you will find either a p or an i. The i means interlace, this is because old TV’s did not have enough bandwidth to fit the whole image on the TV at once, so it would carry every other lines worth of information and then the remaining lines. Technically this is an older technology and less advanced. The p stands for progressive and this is when the whole data is sent over at once and displayed at once. Progressive TV’s can display interlace signals as well. I hope this cleared things up it helped me.