Is there a gem author around you? Did you meet any author of the gems used? Did you contact with any author of the gems used on the Internet? Do you think that "the author is cool!", "the author is awesome!" or "I respect the author!"? Do you want to be a gem author? This talk doesn't describe about how to create a gem because it is easy. "gem" is a package of Ruby library (, tool and so on) for easy to install. This talk describes about developing a library that is gem content. This talk is based on my experience as a library developer. This talk describes about how to write codes, how to write documents, release, support and mental set for a better "library developer". I hope that this talk is a trigger for increasing the number of better "library developers".