Put simply, a musical scale is a series of notes in a specific, consecutive order. Major and minor scales are the two most common types, and they have the following attributes:
They're eight notes long.
The top and bottom notes are an octave apart, so they have the same name.
The series follows a stepwise pattern up and down, and the name of each note in the scale follows the alphabet up and down.
Each scale gets its own wacky-sounding name, like C major. A musical scale derives its name from the following two things:
The scale's bottom note, called the tonic. For example, a C major scale starts on C.
The stepwise pattern used to create the scale. Music has two kinds of steps — half steps and whole steps — which are the building blocks of scales. The "major" part of C major means the third note of the scale is a major third interval above the tonic.
Some white keys have a black key in between and some white keys are side by side:
Two keys side by side (whether black or white) are one half step apart.
Two keys separated by one other key (black or white) are a whole step apart.
Two half-steps equal one whole-step.
The suffixes sharp and flat are used to name the black keys. When you measure half steps up or down, you help define the black keys as sharps and flats. For example, find any D on your keyboard. Move one half step higher and play the black key to the right. That's D sharp. Now play one half-step lower than D. That's D flat.
You can build any scale starting on any root note simply by applying the correct scale pattern, or combination of whole (W) and half (H) steps.
Major scale: Tonic-W-W-H-W-W-W-H
Minor scale: Tonic-W-H-W-W-H-W-W