AccidentalA symbol (sharp ♯, flat ♭ or natural ♮) that raises or lowers a note by a semitone.ArpeggioThe notes of a chord played one after another instead of together.Bar (measure)A segment of music containing a set number of beats, marked off by vertical bar lines.Bass clefThe clef used for lower notes, usually played by the left hand on piano. Also called the F clef.BeatThe steady underlying pulse of a piece of music that you tap your foot to.ChordThree or more notes played together. The most common are triads, built from a root, third and fifth.Chord progressionA sequence of chords played in order, such as the common I–V–vi–IV loop.ClefA symbol at the start of a staff that fixes the pitch of the notes, most commonly the treble and bass clefs.DynamicsHow loud or soft the music is played, marked with terms like piano (soft) and forte (loud).FlatAn accidental (♭) that lowers a note by one semitone.IntervalThe distance in pitch between two notes, measured in semitones or by name (third, fifth, octave, and so on).KeyThe group of notes a piece is centred on, defined by its key signature and tonic note.Key signatureThe sharps or flats shown at the start of each staff that apply throughout the piece.LegatoPlaying notes smoothly and connected, with no gap between them.MajorA scale or chord with a bright, happy quality, built with a major third above the root.MetronomeA device that produces a steady click at a set tempo to help you keep time.Middle CThe C nearest the centre of the keyboard (C4), a common reference point for reading and playing.MinorA scale or chord with a darker, sadder quality, built with a minor third above the root.OctaveThe interval between one note and the next note of the same name, higher or lower (twelve semitones).PedalA foot control on the piano; the sustain pedal holds notes ringing after you release the keys.RestA symbol showing a period of silence, with different shapes for different durations.RootThe note a chord is built on and named after, for example C is the root of a C chord.ScaleA set of notes in ascending or descending order, built from a fixed pattern of whole and half steps.Semitone (half step)The smallest interval on the piano, the distance from one key to the very next key.SharpAn accidental (♯) that raises a note by one semitone.Staff (stave)The five horizontal lines on which music is written; the position of a note sets its pitch.TempoThe speed of the music, measured in beats per minute (BPM).Time signatureTwo numbers at the start of a piece showing how many beats are in each bar and which note gets one beat.Treble clefThe clef used for higher notes, usually played by the right hand on piano. Also called the G clef.TriadA three-note chord made of a root, a third and a fifth stacked together.