GitHub Gist, is very important and make developers life easy by sharing code. Gist are free to create and store in GitHub and they very easy to create. You can create a new gist, modify and delete file. Lastly, there is no need to download or install a program to use gist.
For more details please visit - https://lazypandatech.com/blog/Miscellaneous/27/How-to-create-and-add-GitHub-gist-file-to-your-blog