Thanks to Google's oft-changing logo, I discovered that today is the 57th anniversary of the barcode being patented.
Over those years this machine-readable graphic representation of data has morphed into various forms (a recent case-in-point being the Japanese-designed QR code) but the most ubiquitous example in the UK remains – well, a load of vertical black lines.
For me it's a fine example of simple, practical and understated design. (Apologies if the above image makes your eyes go a bit funny …)