Terms

Duration - The element of time in music
Beat - the underlying pulse in a piece of music. Steady, and not always "heard", but more "felt".
Rhythm - an organized and repeating pattern of beats and syncopations forming a musical idea. (I've modified this to " an organized and repeating pattern of shorts and longs forming a musical idea".)
Tempo - the speed of the beat. Fast, slow, moderate, etc.
Meter - the automatic breaking up of beats into patterns of two or three in our ear when we hear music. "How the beats are grouped".
Measure or "Bar" - when we break up the beats into patterns of two or three, a measure is one complete time through the patterns. Ex. 1 - 2, 1 - 2, 1 - 2 is three measures.

Nonmetric - when the beat is not evident.

Songs for listening
Meter of Four: Wake Me Up: Avicii (phrases pass in four measures, ending with incomplete cadence then ending with complete cadence)
Meter of Three: Say Something: A Great Big World (you may not feel the meter since there is nothing playing or implying the beat really)
Meter of Five: Bury My Lovely: October Project. This one has a set of three beats followed by a set of two beats to make five.

"Turning Time Around" is my term for when you think you are feeling the beat of a song, then something enters to define the beat, and it's not where you thought it was.
My Road Song
My "Road Song" with my daughter's beat.
My "Road Song" with MY beat included.

My song Rhythmic Plexi

Dynamics - The relative loudness or quietness of musical sound (Volume)
Crescendo - gradual increase in volume
Decrescendo - gradual "decrease" in volume
Subito - a sudden change in the dynamic level. It may move from loud to soft or from soft to loud, but it is abrupt.


The Loudness Wars
The "Loudness Wars" is a technique that has been going on for decades in audio production. Each track of a recording is compressed to reduce the dynamic RANGE. The the track is normalized to make it louder. Then the track is compressed once again to reduce the dynamic range even more. Once again, the track is then normalized. This is done several times until the resulting track is very dense. There is no "range" of dynamics, and everything is as loud as it can be without sending the sound into "clipping" or distortion.
Compression is a means of "squashing" the dynamic range, making loud sounds softer, and increasing the volume of soft sounds. This is done to achieve a more uniform volume level throughout a piece of music.
What is the result in the sound of a file processed this way?

Normalize is a means of expanding the dynamic range of audio to the maximum level before "clipping" (distortion). There is no noticeable difference in the quality of the sound, just that it is louder.