Three important concepts should be defined before typesetting: font size, line spacing and kerning. Of course, there are many other related concepts, such as font, font family, thickness, first line indentation, punctuation and so on. But I think these are relatively minor.
Font size and reading speed
The font size defines the size of the font itself. When reading an article, every word is a "point", and a point is one of the three elements of a plane (point, line and surface). The setting of font size depends on the reader's reading speed. The bigger the font, the slower the reading speed will be, and of course the attention to the characters will also increase. In addition to the information contained in the text itself, when the text is enlarged, the details of the strokes will become more and more obvious, and the viewer's attention will be gradually enlarged from the "point" level of each word. The smaller the text, the faster the reading speed. Line spacing: relative distance
Line spacing is the density of two lines of text in a paragraph. The function of line spacing in the article is to effectively guide reading. Too close spacing between two lines of text will cause reading difficulties, while too far spacing will also cause problems.
Row spacing is inseparable from the element "face" that constitutes a plane species. Different line spacing forms the density of the surface, which is the gray level of the paragraph.
Line spacing and line density are inseparable. For example, if the line height of a font is 10px, then if the line spacing is 2px, which is 1/5 times the line height, it will become too crowded and difficult to read. What we graphic designers understand is that the parameter value of character spacing can be set directly in the software, while the character spacing of font designers is a relatively basic work. In font design, every character should set the spacing between words. Too close and too far are not conducive to reading the article. Moreover, in font design, the adjustment between words is also a very tedious and huge work.
In the calligraphy rules of Chinese characters, there is the so-called "qi", which is also the feeling brought by a whole line of fonts, and is inextricably linked with the spacing between words. The so-called gas can also form a line, that is, the play of the "line" element in plane composition.
Then, just like we take the paragraphs between words that have been set and then adjust the spacing between words, it is nothing more than debugging on the shoulders of giants. Therefore, the adjustment between words is also based on the change of existing spacing in the original font design, which we can call character spacing here.
Original spacing of fonts
The most suitable spacing is different for different fonts. We can give an example: Siyuan Songti and Fangzheng Meihei. The two roles are quite different in form. When the character spacing of Siyuan Songti is set to 0, the character spacing is also very different from that of Founder Meihei. The font spacing of Fangzheng Meihei is very wide by default. It can be compared with the character spacing 100 of Siyuan Songti when the character spacing of Founder Meihei is 0.