I have a lot to write so I'll start with this - which is long overdue.
C# is the first black key, one semi-tone from C, one half-step. It sits between C and D. You could also refer to it as Db major/minor (I don't have a proper flat sign) but I'll be sticking to the sharps because they're just something I use entirely over flats (and again, I don't have a proper flat key on my Mac's keyboard and would rather not go to lengths to have to find one to copy here, repeatedly).
If you read what I have below about major/minor differences on the previous posts, go ahead and skip this - it's just for newcomers reading this.
A note on major/minor:
There is an obvious difference between a major and a minor. Wikipedia naturally describes a minor chord has differing "from a major chord in having a minor third above the root instead of a major third." In other words, the third key from the first on a keyboard (not in the chord or scale) would simply be moved a key to the left. In C major, the notes are C-E-G. E is three keys from C; move one key to the left and you're now on E flat or D sharp. Hence C minor. The "minor third" just means the third note in a minor scale.
Ear-wise, the difference is also obvious because minor chords sound darker and moody and tentative while major chords are bright and happy and powerful in contrast. If you've heard any sad songs, they're likely built around a minor scale progression and use minor chords. 'Not Home Today' uses mostly minor chords (E minor and B minor) and is a song about an unfortunate circumstance, with a doom-filled ending. 'Around the Bend' uses largely major chords and is a happy song about friendship and good times. Of course, not all songs operate this way - 'I'm Sorry' by The Payolas has bright chords yet talks about a sellout musician. 'Alive' by Pearl Jam has what people have referred to as an anthemic sound, with great strong major guitar chords and progressions, yet it's about a man who discovers his father died long ago and his mother is virtually attracted to him thanks to his resemblance to his father.
The thing about inversions - where the root note is not the lowest or first note played in the chord - is that it's all the same for every chord major or minor: It's either darker or brighter, in terms of colour as well as personality (though slightly, and it's perhaps more on the main personalities' view or opinion or feeling on something).
Colour: Faint pink, with white.
Light: Cloudy but bright.
Spatial Direction: East
Texture: Soft, like cloud.
C# major on its own without any respective context to music around it is a nice in-between chord for both C and D major. C major is a bright, happy yet down to earth chord, while D major is just plainly happy and considerate, very friendly. C#major could easily be a sister to both chords, or a cousin. She's got a very optimistic point of view and can have her head in the clouds dreaming happily. At the same time she can be direct and get things done. She is good at making goals and working at them; if she has something envisioned for the future, she might be dreamy about it at first, but then she'll make it happen and get there. She's got a warm personality. I'm not sure who I could fit into that chord as a person other than girls I was aware of in school who were noticeably bright, friendly, and on the honour roll. Girls on the Athletic Council seemed like that to me. The only song I can thing of right now that uses C#major is 'Ah! Leah' by Donnie Iris, which uses that note and chord throughout the entire song. The soundtrack to that Breakin' movie from the early 80s uses C#major as its opener and chorus, which is what drew me into the song.
Colour: Dull white, some grey texture.
Light: Cloudy and dull.
Spatial direction: East, southeast.
Texture: Rainy, fluid.
C# minor is the girl with the more reserved, darker outlook. She isn't moody or depressed, but she's cautious and has a negative past. As a result she has a very particular viewpoint of everything, and a precise sense of self-empowerment from her adversities - it didn't kill her, it made her stronger. Therefore she takes her opinions and her perspectives and sees them as defining and more important or relevant than other peoples' because they can't understand what she's had to go through. I knew someone like that for a brief while. 'All That She Wants' by Ace of Base uses that chord (inverted) on the piano throughout the whole song; Chris Foreman of Madness picks each note in the chord on the guitar (that and B minor) throughout the song 'Memories' (the introduction is of the guitar picking each note of both chords from low high strings on the guitar, which sounds melancholy but quite appealing and beautiful). The chord tends to make me think of rain, particularly rain falling on a plaza without observable borders, just a shiny white concrete tarmac glistening in the rain as people with umbrellas walk through it in coats. And it's in Europe somewhere.
Well, I'm happy I finally got to starting the sharps/flats. I'll do D# major/minor sometime soon.