little coloured icons

[radical]

Hi all,

I have a feeling I might have once known and forgotten, but what do the little pink, blue and yellow 'pages' on the far left next to each topic in the list signify?
thanks

[Contessa]

Hey Rad,
If you scroll down the bottom of the a board page, they symbolise the number of responses the thread has received. Blue is normal, yellow is 15+ replies, red is 25+ replies.