[Barnes]

Single space. I learned double and it took a lot of effort to stop. Also, stop underlining text. It's not a typewriter.

There is zero evidence that either single or double spacing improves readability or legibility. The standard for newspapers, magazines, texts, and the Internet is single. The thing that negatively affects readability and legibility the most is the use of non traditional typography conventions like double spacing.

Do it or don't but it's not standard. Write in upside down comic sans for all I care...