Holding the line: a closer look at a common mistake

What kind of error is it?

It's an idiomatic error.

Why do people make this mistake?

People often hear "toe the line" and mistakenly assume it is "tow the line" due to the sound-alike nature of the words "toe" and "tow," and a misunderstanding of the expression's origins.

What is correct?

The correct idiom is "toe the line," which means to conform to a rule or standard. The phrase originates from the idea of lining up with one's toes on a starting line, ready to follow orders or begin an activity.