What is "101"?

Question

IT education

Colleagues, what does "101" mean in the name of the courses? For example, today the Energy 101 course was launched on Coursera. The lecturer simply called it “Energy one-oh-one,” as if everyone understood everything. And in other courses I met it. What the heck?

Answer 1

Classes are coded as 3-4 subject letters + 3 class level digits. Hundreds in code roughly corresponds to a 4-year college year.
1xx - freshhman (1st year) - introductory classes
2xx - sophmore (2nd year) 3xx
- junior (3rd year)
4xx - senior (4th year) - specialized classes of an increased level of complexity
than his year of study.
For masters and graduate students, classes will respectively start from 5xx-9xx.
Tens and hundreds in the number denote different classes, most often the numbering goes in order of increasing complexity, or class dependency. So, for example, to take the class FIN345 (“Finance - Intermediate Level”), you must definitely take FIN302 - “Introduction to Finance”, etc. And FIN445 will probably be an order of magnitude more complicated than FIN345.
In total, 101 is the most basic class in any subject, for example, MAT101 - an introduction to mathematics or BIO101 - an introduction to biology.

Answer 2

Wiki
The term 101 (pronounced "One-oh-one") often indicates an introductory level of learning.

Answer 3

I guess it's the level of difficulty...