C#/Db
D#/Eb
F#/Gb
G#/Ab
A#/Bb
These notes sound the same, but they are written differently. This can be confusing, but it's important to understand the difference between these notes.
For example, C# and Db are both the same pitch, but they are written differently. C# is written with a sharp (#) sign, while Db is written with a flat (b) sign. This means that C# is played by pressing the black key to the right of the white key C, while Db is played by pressing the black key to the left of the white key D.
D#/Eb, F#/Gb, G#/Ab, and A#/Bb are all the same as well, just like C# and Db, they are just written differently
It's important to understand the difference between these notes because it can affect how you play music. For example, if you are playing a song in the key of C major, you would use the C# note. However, if you are playing a song in the key of Db major, you would use the Db note.
Also, if you are trying to transpose a piece of music to a different key, you will need to know the difference between these notes. For example, if you want to transpose a piece of music from the key of C major to the key of Db major, you would need to change all the C# notes to Db notes.