Calpol is a form of medicine for children. It comes in various varieties for different age groups (differing by concentration of the active ingredient, and flavour). Wikipedia tells me it is available in the UK, Ireland, India and Cyprus. The active ingredient is paracetemol (Tylenol for those in the USA). Although I am sixteen years old, and well past the age at which Calpol is marketed (the oldest is for six years old and above), I still take the version for babies younger than one year. It tastes the best (pink flavour) and makes me feel better, although whether that's down to the drug or the placebo effect I do not know.
It comes in a glass bottle with a child-proof lid, and a spoon for measuring dosage is included in the box. It is also available in pre-measured sachets, which are very convenient when travelling.