What makes a music piece?

What makes a music piece? 

When creating a music piece there are many important factors to consider such as:

• The key - whether the piece is a happy or sad song
• Lyrics and melody - what the meaning is behind it
• Tempo - The pace of the piece whether its slow or fast
• Instrumentation and motif - the character of it, how it flows
• Structure and themes - the story behind it
• Rhythm and meter - what style is the piece?
• Harmony and dynamics - How does it makes you feel, what emotions do you relate to it.

Each of these hold a important role when writing or composing music, they all intertwine together and support each other.