I'm not particularly fond on extremely detailed backgrounds on my characters. I tend to forget details, things that I wrote down as important or defining end up not being so, quircks change or are never used...you get the idea. I prefer to start with a simple concept and play the character once or twice and let it grow organically. I remember the details better in those cases.
I also have a big problem called 'I don't read' (yes, I know it's a flaw), so I'm not particularly fond of other people having very long and detailed backgrounds unless I'm invested in a plot with them, or their character managed to call my attention during an actual scene. But then I'd probably only read the basic information and try to get all the other details by interacting in-character.
With that said, I do write backgrounds for my characters. They are pretty barebones, to the point (sometimes, anyway) and aren't good literature (you can see for yourself on the wiki page of my main character). They are more like internal notes than anything else: if I forget anything, opening the page and looking it up should be easy since it's a short profile. It doesn't work with special mannerisms and quircks, though. I had a character in TERA whose biography said she always had to have something in her hands. It never came up in actual roleplay and, by the time I remembered or read it in the background, it was a bit too late because I had spent various hours where she had absolutely nothing between her hands.
So my advice is to make a basic draft. Then roleplay a bit in a casual scene (like a tavern, or a random walk-up in the street) to see how the character develops organically from there (and to see how you play him or her), and then go back and try to marry your draft with your roleplay, filling out details that seem necessary to define the character as a person.
I also have a big problem called 'I don't read' (yes, I know it's a flaw), so I'm not particularly fond of other people having very long and detailed backgrounds unless I'm invested in a plot with them, or their character managed to call my attention during an actual scene. But then I'd probably only read the basic information and try to get all the other details by interacting in-character.
With that said, I do write backgrounds for my characters. They are pretty barebones, to the point (sometimes, anyway) and aren't good literature (you can see for yourself on the wiki page of my main character). They are more like internal notes than anything else: if I forget anything, opening the page and looking it up should be easy since it's a short profile. It doesn't work with special mannerisms and quircks, though. I had a character in TERA whose biography said she always had to have something in her hands. It never came up in actual roleplay and, by the time I remembered or read it in the background, it was a bit too late because I had spent various hours where she had absolutely nothing between her hands.
So my advice is to make a basic draft. Then roleplay a bit in a casual scene (like a tavern, or a random walk-up in the street) to see how the character develops organically from there (and to see how you play him or her), and then go back and try to marry your draft with your roleplay, filling out details that seem necessary to define the character as a person.