The number of seals varies according to the situation of calligraphy works. Generally, the top right is a leisure stamp, and the bottom of the signature of the work is a famous stamp (sometimes two stamps). Depending on the layout of calligraphy, other seals are sometimes stamped-these are all stamped by the author. The contents of stamps can be the name of learning, words of encouragement, zodiac signs and so on. There are also many chapters you see, which are stamped by people or units who have seen this calligraphy, representing the collection or reading of this calligraphy work. Of course, many books have inscriptions at the back, and only those who write well dare to do so. )
As for why the seal script was used: Because the seal script was the most popular font in the early Qin Dynasty, many seal scripts chose the seal script font in order to reflect the source. In fact, there are many seal fonts, such as Oracle Bone Inscriptions and Lishu, and there are also many seals. You don't know much about it!