Roman numeral code: I
Scale notes: 1, 3, 5
Attributes: root, beginning, essence, foundation
1 is the frame or skeleton of the key that it represents. It is sometimes called the tonic chord. When sounded it defines that key to our ears.
In the examples you will hear some notes in the melody that are not part of the 1 harmony; but they are transitory and the underlying harmony remains 1.
Harmonically 1 is neutral. It can be inserted into any progression of chords without changing the character of that progression.