Common chord progressions and keys can vary across different genres of music, but certain patterns have become widely used due to their pleasing and familiar sound. Here are some common chord progressions and keys:

Common Chord Progressions:

1. I-IV-V:
   • Example in C major: C – F – G
   • Example in A minor: Am – Dm – E
2. I-V-vi-IV:
   • Example in G major: G – D – Em – C
   • Example in E minor: Em – B – C – Am
3. vi-IV-I-V:
   • Example in D major: Bm – G – D – A
   • Example in B minor: G#m – E – B – F#m
4. ii-V-I:
   • Example in C major: Dm – G7 – C
   • Example in A minor: Bm7(b5) – E7 – Am
5. I-vi-ii-V:
   • Example in F major: F – Dm – Gm – C
   • Example in D minor: Dm – Bb – Em – A7
6. iii-vi-ii-V:
   • Example in E major: G#m – C#m – F#m – B7
   • Example in C# minor: Em – Am – Dm – G7
7. I-IV-ii-V:
   • Example in A major: A – D – Bm – E
   • Example in F# minor: F#m – B – G#m – C#7

Common Keys:

1. C Major / A Minor:
   • The key of C major and its relative minor, A minor, are common due to their lack of sharps or flats, making them accessible for musicians.
2. G Major / E Minor:
   • G major and its relative minor, E minor, are popular for their bright and open sound.
3. D Major / B Minor:
   • D major and its relative minor, B minor, are used for their warm and rich qualities.
4. A Major / F# Minor:
   • A major and its relative minor, F# minor, are favored for their versatility and expressive potential.
5. E Major / C# Minor:
   • E major and its relative minor, C# minor, are used for their energetic and powerful feel.
6. F Major / D Minor:
   • F major and its relative minor, D minor, offer a balance between brightness and depth.
7. Bb Major / G Minor:
   • Bb major and its relative minor, G minor, are chosen for their distinctive tonalities.

Remember that these progressions and keys are just starting points, and creativity often comes from experimentation and pushing boundaries. Different genres may have their own conventions, and individual songs can deviate from these common patterns to create unique and memorable compositions.

Chords in each key

Here are the chords that make up each key in the diatonic major scale. Each key has seven diatonic chords, built on the notes of the major scale.

C Major:

1. I – C major (C-E-G)
2. ii – D minor (D-F-A)
3. iii – E minor (E-G-B)
4. IV – F major (F-A-C)
5. V – G major (G-B-D)
6. vi – A minor (A-C-E)
7. vii° – B diminished (B-D-F)

G Major:

1. I – G major (G-B-D)
2. ii – A minor (A-C-E)
3. iii – B minor (B-D-F#)
4. IV – C major (C-E-G)
5. V – D major (D-F#-A)
6. vi – E minor (E-G-B)
7. vii° – F# diminished (F#-A-C)

D Major:

1. I – D major (D-F#-A)
2. ii – E minor (E-G-B)
3. iii – F# minor (F#-A-C#)
4. IV – G major (G-B-D)
5. V – A major (A-C#-E)
6. vi – B minor (B-D-F#)
7. vii° – C# diminished (C#-E-G)

A Major:

1. I – A major (A-C#-E)
2. ii – B minor (B-D-F#)
3. iii – C# minor (C#-E-G#)
4. IV – D major (D-F#-A)
5. V – E major (E-G#-B)
6. vi – F# minor (F#-A-C#)
7. vii° – G# diminished (G#-B-D)

E Major:

1. I – E major (E-G#-B)
2. ii – F# minor (F#-A-C#)
3. iii – G# minor (G#-B-D#)
4. IV – A major (A-C#-E)
5. V – B major (B-D#-F#)
6. vi – C# minor (C#-E-G#)
7. vii° – D# diminished (D#-F#-A)

F Major:

1. I – F major (F-A-C)
2. ii – G minor (G-Bb-D)
3. iii – A minor (A-C-E)
4. IV – Bb major (Bb-D-F)
5. V – C major (C-E-G)
6. vi – D minor (D-F-A)
7. vii° – E diminished (E-G-Bb)

Bb Major:

1. I – Bb major (Bb-D-F)
2. ii – C minor (C-Eb-G)
3. iii – D minor (D-F-A)
4. IV – Eb major (Eb-G-Bb)
5. V – F major (F-A-C)
6. vi – G minor (G-Bb-D)
7. vii° – A diminished (A-C-Eb)

Considerations

These chords represent the diatonic harmony within each major key. Remember that lowercase Roman numerals indicate minor chords, and uppercase Roman numerals indicate major chords. The vii° denotes a diminished chord.