Final answer:
Critics are the category of Web 2.0 participants who engage in activities like blogging and posting reviews, typically falling in the late teen to mid-twenties age range.
Step-by-step explanation:
The category of Web 2.0 participants who are predominantly involved in blogging, posting ratings and reviews, and are generally in their late teens to mid-twenties, is Critics. This group includes not only professional writers who review creative works such as films, TV shows, books, and visual arts but also everyday consumers who share their opinions on various platforms.
As part of the interactive nature of Web 2.0, these individuals contribute to the participatory culture by expressing their viewpoints, which in turn influences others' perceptions and choices. Through mediums like social media, video sharing sites, and consumer review platforms, they actively shape the dialogue around products, entertainment, and services.