That is a tamper evident device it allows you upon picking the bottle off of the shelf immediately identify if the bottle has been opened. It wont prevent tampering as anyone can still open the bottle and add any number of things to the liquid (such as poison or chemicals) but anyone who picks up that bottle will know the bottle was tampered with in some form.
We can see these kinds of technologies everywhere when you stop and look around. Very often electronic devices such as game consoles and computers will have tamper seals installed inside that would reveal if the device had been tampered with. This is predominantly done for warranty purposes as most companies will not cover warranty if a product has been tampered with.
Now these seals are essentially little more then simple stickers and can not prevent the device from being tampered with however if someone does tamper with the device then you will be able to tell by looking at the sticker. In the 1980's just after the case of cyanide pills being placed in Tylenol bottles scare around the Chicago Illinois area the US Government instituted the Federal Anti Tampering Act of 1983. This allowed for prison sentences to anyone who tampered with pharmaceutical medication and called for the private sector to develop tamper seals. Today we can see tamper devices on currency in financial institutions. Once again these devices do not prevent tampering but they do produce evidence of tampering.
This article is merely to serve as an introduction to the many different kinds of tamper evident devices In the coming months we hope to advance this into a much larger series.