What has caused changes in how the game of football has changed

I chose to write this topic because many people are questioning how football has changed over time. They actually don’t know the real causes of what has changed football over time. One major reason football has changed due to the immense addition of the use of technology. For example, In 1869, A touchdown was always 100 % confirmed. But, due to technology, touchdowns that are scored today are not always confirmed because they can be reviewed after the play or if the team challenges the call. There many other causes to the change of Football which is America’s most played and watched sport.