web - Screen resolution 1024px or 960px? -

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• why width 960px? 7 answers

back in day use design website resolution:

1024px(width) 768px(height) 

but avoid getting scrollbar appearing both sides use smaller resolution, may be:

1000px(width) 620px(height)---rectify me if i'm wrong on 1 

but main concern how did 960 grid system comes place? know laying out contents accordingly within 960px grid, if why not use 1000px instead? since use size during time?

the reasoning this:

1024 x 768 common resolution @ designs aimed.

subtract 24px scroll bar - 1000px;

960px leaves additional breathing room , importantly - has many more factors (division) 1000px. 960 therefore ideal choice grid system.

here factors:

960

1 2 3 4 5 6 8 10 12 15 16 20 24 30 32 40 48 60 64 80 96 120 160 192 240 320 480 960

1000

1 2 4 5 8 10 20 25 40 50 100 125 200 250 500 1000

credit answers on post: why width 960px?