We take fonts for granted these days, its good to pause and look back at some typography history to see how and why things were made. When I work on design for a project, I take into consideration the form of fonts as well as the functionality.
Serif is a french word and, you can open the link to the google translation and hear the way it is said in french.
Wood image created by Rawpixel.com - Freepik.com
Many years ago before computers letters were carved on wood using a chisel. The tools would not blunt and not so accurate so when they carved out the letters a little would be left at the end. The printing press was used to make print books and newspapers. If you are interested in reading up about it follow this link.
Google defines a serif as : a slight projection finishing off a stroke of a letter in certain typefaces.
On paper it's easier to read serif fonts, because the serifs help the letters blend together and it is physically easier on the eyes and brain.
Wikipedia defines it as:
In typography, a serif (/ˈsɛrɪf/) is a small line attached to the end of a stroke in a letter or symbol. A typeface with serifs is called a serif typeface (or serifed typeface). A typeface without serifs is called sans-serif or sans serif, from the French sans, meaning "without". to read the rest of the article go here https://en.wikipedia.org/wiki/Serif.
Once modern equipment and tools became available the fonts started improve as they were able to get rid of the serif. The reason we think of serif fonts as old is because all the old scripts and books were with a serif, all modern fonts had the serif removed.
I like to use Sans-Serif fonts for my designs as they look more modern, let me know which ones are your favorite fonts.