And so are every upper-case letter. And if you want, you can modify your keyboard layout to swap the - and _ and no longer have to reach for the shift key at al

And so are every upper-case letter. And if you want, you can modify your keyboard layout to swap the - and _ and no longer have to reach for the shift key at all. (I'll just laugh at the argument that underscores causes problem with line width limitations.) I prefer the underscore style as I find the names more legible, it's easier to see where each particle starts and ends. It's particularly evident when using acronyms: read_JPEG_image is much more legible than ReadJPEGImage. Many style guide resort to lower-casing acronym due to that: ReadJpegImage.