A scale is made of a progressive series of pitches. A step is the term for the space between pitches. Two spaces equal a whole step, while one space is a half step. This means the distance between C and D is a whole step, because of the sharp/flat between the two pitches. From C to C-sharp is a half step since no other pitches exist between the two notes.
Major scales consist of seven pitches with the first pitch doubled in the next, highest octave for eight notes. All Major scales follow a pattern of two whole steps, one half step, three whole steps, one half step. The name of the key of the scale derives from the pitch on which the scale usually begins and ends. Musicians refer to pitch as the tonic.
Minor scales also have seven pitches, plus the first pitch doubled an octave above, but minor scales have three different patterns. The natural minor will begin with a whole step, followed by a half step, two whole steps, one half step, two whole steps. The harmonic minor consists of a whole step, half step, two whole steps, half step, a whole step plus a half and a half step. The melodic minor follows a pattern of whole step, half step, four whole steps, half step. Minor scales also begin and end on the tonic.
Pentatonic scales have only five pitches, beginning with the tonic. A pentatonic scale is basically a Major scale with pitches 4 and 7 missing,
Chromatic scales have only half steps. A full chromatic scale will consist of 12 different pitches plus an additional raised octave first pitch. Although chromatic scales begin and end on the same pitch an octave apart, no tonic exists since each note is equally distant.
Knowing what key signature a scale is in makes it easier to play. Major, minor and pentatonic scales have key signatures. Chromatic scales do not. The key signature is to the left of the scale and shows which sharp or flat notation raises or lowers certain pitches. Key signatures will have either sharps or flats, but not both. Major and minor scales sometimes share the same key signatures. To determine whether a key is Major or minor, find the tonic, which will usually be the beginning and ending pitch of the scale.