Final answer:
A hashtag on microblogging sites indicates that a set of posts are on a similar topic. They are a key part of categorizing and discovering conversations on social media platforms, and play a pivotal role in movements like 'hashtag activism'.
Step-by-step explanation:
On microblogging sites, a hashtag is used to indicate that a set of posts are on a similar topic. Hashtags serve as a means for users to categorize posts, making it easier for others to find and engage in conversations on a particular theme or subject matter. This can be seen in movements like Black Lives Matter, where the hashtag not only represents an organization but also a general sentiment and an idea with deep personal meaning.
Moreover, social media platforms like Fac ebook, Twi tter, and T ikT ok play a significant role in fueling social change and political expression through what is sometimes referred to as "hashtag activism". Such forms of digital engagement demonstrate the far-reaching impact social media can have, especially when conveying messages quickly across large audiences.