# Accidentals and key signatures on the staff

*Module 3 · Lesson 5: Reading music for bass · BazzLow*

> Know how long an accidental lasts and what a key signature does on the staff.

Before this lesson: [3.4 Reading rhythm on the staff](https://bazzlow.com/en/reading-music/reading-rhythm-on-the-staff/) · [1.3 Sharps, flats and enharmonic notes](https://bazzlow.com/en/notes-and-fretboard/sharps-flats-enharmonics/)

Lesson 1.3 introduced sharps, flats and naturals. Here is how they are written on the staff, and how long they last.

## Accidentals

An **accidental** (♯, ♭, ♮, 𝄪, 𝄫) is written just *before* the note it changes. It applies to that note and to every later note **on the same line or space** until the **end of the bar**: the barline cancels it. Strictly it applies only in the same octave. Many editions add reminders anyway.

A **courtesy** (or cautionary) accidental, sometimes in brackets, is a reminder in the next bar. It is not required, but it is helpful.

> **Diagram:** One bar. First note: F♯, with the sharp written. Second note: another F on the same line, so it is still F♯. Third note: an F in a different octave, so it is a plain F. Fourth note: a natural sign cancels the sharp, so it is F.

## Key signatures

A **key signature** is a group of sharps *or* flats written right after the clef, on **every line** of music. It applies to **every note with that letter name, in every octave**, for the whole piece, until a new key signature appears. A key signature never mixes sharps and flats.

Example: one sharp on the F line means every F is played F♯, unless an accidental says otherwise.

> **Diagram:** A key signature of one sharp on the F line. Both Fs in the bar, in different octaves, are F♯; G and A are natural.

Which key signatures exist, their order and which key each one means are explained in Module 5.

## Try it

Read both diagrams and say each note name before playing it. Then play them.

## New terms

- accidental
- courtesy accidental
- key signature

Page: https://bazzlow.com/en/reading-music/accidentals-and-key-signatures/