Final answer:
The second category of social media is 'bookmarking,' with popular sites like Delicious and StumbleUpon allowing users to save and share web resources.
Step-by-step explanation:
The second category of social media, according to the types listed by Dollarhide and Drury, is bookmarking. Social bookmarking sites allow users to save, organize, and manage links to various websites and resources around the internet.
These platforms are essential for individuals looking to bookmark and share web pages that they find interesting or useful.
Examples of bookmarking sites include Delicious and StumbleUpon. Users can discover content bookmarked by others, which can be particularly useful for exploring curated content and collaborating with peers on collecting resources for research or leisure activities.