Allegro
Fast, lively, cheerful.
What it means
Allegro means in Italian first of all “cheerful, merry” and only secondarily “fast”. This double meaning is important for understanding: the marking calls not only for a rapid tempo but for an alert, purposeful attitude. As a guide, around 120 to 156 beats per minute is frequently named, yet the span is large and depends on time signature, note values and era.
In relation to the neighbouring words: Allegretto is the milder, Allegrissimo the intensified form. Presto means a distinctly faster tempo, Vivace stresses liveliness rather than pure speed. Allegro frequently appears with additions that make it precise or qualify it — ma non troppo, assai, moderato, con brio — and these additions often alter the tempo more strongly than the base word itself.
In the notation
The marking stands above the first system and as a rule becomes the name of the movement; to speak of “the Allegro” of a symphony means the movement so headed. Within a work Allegro marks, after a slow introduction, the beginning of the main section. Metronome figures beside it often come from the editor and are to be read as a guide.
Musical use
Allegro is the standard designation of the first movement in the sonata, symphony, string quartet and solo concerto of the Viennese Classicism. There the movement is at the same time the carrier of sonata-allegro form, so that in practice the word denotes more than a tempo: a movement type with a formal claim of its own. Closing movements too frequently bear the marking, then often with an intensifying addition.
Performance practice
Find the tempo in which the fastest figures still stay clear and the themes still stay speaking. Count, depending on the time signature, in larger units, so that the movement does not fall apart into single beats. Work out the metric emphases — an Allegro lives from the gradient between heavy and light beats, not from continuous accentuation. And practise slowly with the same articulation you will later need; at tempo an imprecise tone production can no longer be corrected.