Analysis and composition of a 3 part lied structure and a rondo structure as found in songs and including an alternation of verses and choruses. Originally the word "lied" (German origin) meant "song". So it is a vocal piece based on a poem and saying by a voice solo, accompanied by a piano or an orchestra. The text and music are synchronized and are modified acording to the poem and the feelings it inspires. The "lied" tructure that interests us here, is a ternary form that often feeds the slow parts of the symphonies for example. This tripartite structure which we will call here "A B A" begins with by a theme A played in the main tonality, followed by a second central theme "B" which is generally played in neighbour keys, close to the main key, in other words: the sub-dominant, the dominant or the relative. In order to conclude, we find a return of the A theme, named A', because slightly varied, in the main key. Initially, the "rondo" is a vocal musical form that alternates a chorus with several verses. It is therefore the ultimate structure of a song. We can consider that the "rondo" is an extension of the previous song form, by alternating an A chorus with several verses: B, C, D etc .. In fact, we have a first ternary form ABA then ACA, ADA etc. ... The piece begins with a single theme A (chorus), given in the main tonality, then a first verse B played in a neighboring key, a return of the A Theme in the main key, then a C theme or second verse, in the neighboring key and so on.