Abstract: A music composing system comprises a plurality of music composing blocks 20, 30, 40, 50, 60. Each block comprises a music composing means 16 for composing modified music based on initial and target music sections provided to the block. Block 20 stores initial music I2. When a user places block 20 within a predetermined range of block 30, block 20 transmits its initial music section 12 over a wireless Local Area Network 100 to block 30. Block 30 then composes a modified section of music M3 on the basis of its initial music section I3, using the received initial music I2 of block 20 as a target. Block 30 produces a plurality of copies of initial music I3, and mutates each copy of the music to provide a plurality of mutated sections of music. Block 30 assesses the similarity of the mutated sections of music to the target, I2, and retains those mutated sections which are more similar to I2 than its initial music I3.