Basic formatting HTML question

Greetings friends and neighbors!

I'm fairly new to HTML and so a pretty basic question....

On a page with all text, when the lines wrap at the right, some words butt
right up to the very edge of the screen.  This makes it look like the text
runs off the screen, even though it doesn't.

I think I have seen code that makes the text take up only a certain amount
of the screen -- say 95%.  Can someone pls give me a hand on this?

Thanks much!

Fred