Icons: What are the most intuitive indicator icons for a web application to mean "not yet started," "in progress," and "completed"?

Based on this... "not yet started," "in progress," and "completed." I can see yellow, green, and red (respectively) working for me.

Don't use those colors as red/green is the most common form of color blindness and not helpful for those people.

Not yet started -- black In progress -- grey Done -- white. Or Not yet started -- no bar In progress -- some bar Done -- all bar. Or Not yet started -- nothing In progress -- greyed out checkmark Done -- checkmark

Also, you need to distinguish between status indicators and controls. A green button as a control would intuitively indicate "press this to start", but as a status indicator, it more likely would indicate "in progress". A red indicator as a control would indicate "press this to stop", but as a status indicator, it would indicate "has stopped". "In progress" only has meaning as a status indicator, not a control; and in that context a flashing green would be familiar, yellow more obscure. If something is "in progress", of course, the only relevant control would be "press this to stop", which would naturally be a red color. So basically you need to decide if you're making your controls and your status indicators distinct, or combining them. Combining them is what poses a bit of a challenge and perhaps you should avoid this (assuming you're making controls, as well as status indicators). But, again, as tempting as it is to use these familar colors, they have the great vice of being the most common color-blindness colors. A compromise would be to use these familiar colors in the familiar ways, and use text as well: "Ready", "Working", "Complete", for example. I'm definitely not an artist or graphic designer, but these http://www.kmellis.com/Icons.html I made are examples where the text (though hard to read) would make it unambiguous for even the colorblind; but would signal at a glance the current status. On Preview: ROU has some good suggestions.

I'd go with ROU's suggestions of picking a single hue and using different saturation to indicate progress. The problem, as I see it, with the red/yellow/green analogy is that it's not a status indicator as much as it is an action indicator. When I see a red light, I interpret it as "I'm being told to stop", not "The traffic is currently at at stop."

For what it's worth, here in Korea (and I assume probably elsewhere in NEAsia), when stock market/exchange rate arrows are shown on the news to indicate movement, 'up' (ie good) is always red, and 'down' (ie bad) is always green or blue. Red being a positive colour, basically. Oddly, stop signs and traffic lights are identical to North American colour schemes, though. Tangential, but possibly significant, depending on your target audience.

green = good. red = bad. that's my interpretation, as a luser. if i see red, something's been done wrong. if i see green, it's good. as a progress indicator, bars work much better than traffic lights, i believe, and I think that's why you see so many interfaces doing progress reporting with bars -- not red and green lights.

Another vote for ROU's approach. If I see red (or perhaps orange--any hot color), it's something I need to pay attention to--something must have gone wrong. If I see gray, or any unsaturated color, I can afford to skim past it. If you need some kind of non-linguistic symbols to go with the colors, something like [bullet] [ellipsis] [checkmark] [exclamation point] perhaps.

In addition to the color-blindness thing, remember that in some countries, yellow comes between red and green, not between green and red. That'll throw off your symbolism a little bit.