What is a serif font? What is sans serif? Why care?

Serif fonts are fonts which have 'serifs', the ticks on their ends. Sans serif fonts are sans (without) the ticks.

Serif fonts like Garamond and Times New Roman are used in printing. Books, reports, leaflets and brochures are printed in serif fonts. Because it is easier to read serif fonts on paper. In my book, For Brand's Sake I had used Merriweather from Google.

Sans serif fonts are easier to read on screens. That's why apps, websites and presentations use or should use sans serif fonts. This rule applies when there is a lot of text. When you have just a few words, the readability of both font types do not differ a lot.

If you are making a presentation, do use sans serif fonts. You can download a good font from Google fonts. Try fonts like Rubik, Nunito Sans, Poppins or Roboto.