We are surrounded by logos or " a graphic element, symbol or icon" (ref: http://en.wikipedia.org/wiki/Logo) which help us live our lives and also can save our lives. This following article brought this to mind:
http://news.bbc.co.uk/1/hi/health/6120138.stm
We're always looking for a personal referral and logos do this too! They can act as a stamp of approval such as the recycling logo
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As a footnote to logos as guidance I thought I'd mention road signs and they way their iconography has passed into design: check out the lousebusters logo!http://news.bbc.co.uk/1/hi/health/6111476.stm
From no right turn to ghostbusters to lousebusters. Nit anyone?