A music melody without chords to accompany it will feel very bare and dull. Since the days when early music began by knocking sticks and stones, music and musical instruments have developed progressively to the diversity that we have today.
What are the two basic 'ingredients' that we find in music? One is the melody and the other is the accompaniment to compliment the melody. While the melody consist of stringing together single music notes to form a tune, there is much more happening in the accompaniment.
The accompaniment in popular music today comes from the drummer, the guitarist and/or keyboardist, and the bassist. These musicians form the backbone of a musical performance. There is also the possible addition of other musical instruments to add more 'color' to the music being performed.
Improvisations are primarily based on the chords of the song. One will require ear training, music theory and application to understand and appreciate chords. Being able to identify the type of chord to respond to it with an improvised line instantaneously would be the ultimate achievement in the music making process for any musician. This would have to be learned, and practiced constantly.
In improvisations, there are no notes to read and play. Everything is the perception of the musical mind. What do you hear? How do you want to respond? You will need to consider your overall skills to be able to improvise. To lead students into improvisation, I begin with chord studies. Below is a clip of my recent session with the students.