Recently, curation practices start to develop in GitHub, where developers systematically put efforts to select, evaluate, and organize existing artifacts for the purposes of preservation and future use in software development. Curation practices in social media sites, such as Twitter and Pinterest, have been investigated, raising questions about the nature of collaborative curation in a professional/product-oriented site. In this study, we identify and characterize curation projects hosted on GitHub, and compare curation projects with software projects to study how this practice takes place and how it is different from the original use of GitHub. We find that curation has emerged as a highly popular category of GitHub project, which is directed to learning and professional development, and curation practice leverages collaborative tools and practices native to GitHub. Although curation projects and software projects use the same set of activities for development, they are different from each other in terms of the quantity of each type of activity performed by developers.