The pinyin on it is Ding. For convenience, some netizens use the initial d instead of the top word. Top, support, identify and appreciate. More common in thread posts, indicating understanding and approval of the poster's point of view.

Online forums have gradually improved the technology of high-quality post topping, which makes the word "topping" have the meaning of recommended reading. In the forum, new posts always appear on the front page of the forum, that is, at the top. With the release of new posts, the position of old posts in the forum will decline, sometimes a few pages later, and it is not easy for more people to find them. Good posts are generally expected to be seen and shared by most people. So make comments at the back of the post to make the post rise to the top. For convenience, most people like to write a word: "top", which means to top the post and not to come down again.