Music is an art form and cultural activity, and its medium is sound waves (a kind of mechanical waves) organized according to time and law.
Its basic elements include strength, tonality, duration and timbre. These basic elements combine with each other to form the common "formal elements" of music, such as rhythm, melody, harmony, strength, speed, mode, form and texture. The formal elements of music are the means of expression of music.
Different types of music may emphasize or ignore some elements. Music is played through various musical instruments and vocal techniques, which are divided into instrumental music, vocal music (such as songs without musical instruments) and works combining singing with musical instruments.
In the most general form, music is described as an art form or cultural activity, including the creation, performance, evaluation, music history research and music teaching of music works.
Ancient Greek and Indian philosophers defined music as tones arranged horizontally as melody and vertically as harmony. Common sayings such as "all fields are harmonious" and "this is music in my ears" point out that music is usually an orderly and pleasant idea.
But John Cage, a composer in the 20th century, thinks that any sound can be music. For example, he said, "There is no noise, only sound."