In music theory, you’ll hear the two terms major and minor frequently being used. They refer to the tone of a piece, specifically a scale, key, or chord.

For major keys, the tone is often joyful, upbeat, merry, or peaceful. These keys are more frequently used than minor keys, probably because music more often demonstrates positive emotions than negative ones. In Stevie Wonder’s Happy Birthday, the choruses are all major and sound happy:

On the contrary, minor keys create a melancholy, moody, sad tone. For most of Chopin’s Funeral March below, a sombre mood is created through it being in a minor key:

Bill Bailey humorously explains the difference between major and minor in this short video:

Image: https://aftersectionals.com/wp-content/uploads/2017/05/MAJOR-1.png