As a way of showing how NFL franchises have changed over the years, someone has created a great GIF that shows the evolution of each team's logo.
Eric Orvieto of Yahoo Sports went through the history of the NFL and compiled every insignia each of the 32 current franchises has had. He turned that research into an awesome GIF that shows when a logo changed or an expansion team joined the league.
From the first year of the NFL (1920) through 2015, there has been plenty of change.
This NFL GIF comes nearly a week after Redditor gordontrue made a logo evolution for NBA teams: