What is the purpose of filler Arcs in an Anime?

What is the purpose of Filler arcs in an Anime, some popular Filler arcs are the The Whole of One piece marineford Arc, If I am incorrect, I am sorry, I just finished watching One piece, another example of a filler arc is the whole of Naruto episode 198-220. I am going to be honest I never finished watching Naruto, it was just way to long. I really hope that if One piece filler arcs were deleted from the series, it would not affect the plot of the series.<br><br>&#x200B;<br><br>Again, thanks for all the information. Now that I understand.