Since 1455 we no longer must use only the handwritten word. Johannes Guttenberg (in the opinion of some the most influential person of the second millennium) developed the printing process and printing press. The letters then were ornate, the alphabet included characters found only in Old German. Gothic Script, or Blackletter, was the name given to his font. Let’s remember that it took nearly a lifetime for a monk to hand-copy the Bible. No wonder that a big part of society at that time was illiterate!
Until the 18th century most of the typefaces were serif-adorned. If you are not sure what a serif is- it’s the little cross-bar ending a line such as little feet on the capital A. It gives the letter a finished look. See Times New Roman for references
There was a theory that those little dashes on the bottoms of letters mostly allowed the eye to move from one to another quicker. It’s debatable, I think.
The shapes of serifs, much like the shape of the letters themselves changed over time. They evolved and devolved-depending on your definition of progress. Initially, the serifs were bracketed, as the ink would naturally fill the angle where they met the line of the letter.
EX An example is Garamond and its successor Baskerville. In their evolution, serifs started slanted (in Garamond) when on the top of the letters, then over time became straight, then thick, then thin.