Tironian notes are like secret codes that people used to write down what they wanted to say very quickly without using too many words. They were invented a long, long time ago by a man named Tiro, who was a secretary for a famous Roman leader named Cicero.
You know how you can draw a picture of a flower instead of writing out the word "flower"? Tironian notes are kind of like that. They use little symbols instead of words to make writing faster and easier.
For example, instead of writing out the words "and," "or," or "in," you can use little symbols that look like "&," "/", and a backwards "c". If you want to write out the word "et," which means "and" in Latin, you can use a little symbol that looks like two lines coming together at the top, kind of like a squished letter "S".
People used Tironian notes for a long time, all the way up until the Middle Ages. They were really handy for taking quick notes during meetings or lectures, and they allowed people to write down information quickly and easily without having to worry about spelling or grammar. Cool, huh?