Sometimes making text bold makes it easier to read or stand out among competing elements on the page.

But what happens if you start making everything bold?

I describe it like this.  Bold is like adding sugar to your coffee, just enough makes it taste great, and a little too much ruins it.

Here is another way to describe why you shouldn’t abuse bold.  If you make everything bold, then nothing is bold. Bold by its definition is to stand apart; if everything is the same then nothing is standing out anymore.  Try selecting a fuller or broader font instead, then when  you need to use bold it will work.