There are some trademarked brands which have entered the English language as the word to use for any brand of that item. Sellotape, Hoover and Biro are all examples of this. The one I tend to use the most is Google. The latest word to be added to that list is iPad, which now seems to be the generic term for a tablet computer.
The trouble with this, though, is that brands which become synonymous with the product’s identity often lose the trademark altogether. If it is legally deemed to be too “generic” to be a trademark, then inferior products can use the name on their own packaging. This can be demonstrated with the case of aspirin. Aspirin was developed by a German company, Bayer AG, and was registered as a trademark in 1899. The company held the worldwide patent, but in 1917, Bayer’s patent for the product expired. Following World War I, aspirin lost it’s status as a registered trademark in the USA, UK, France and Russia as part of war reparations. Today, Bayer still holds the trademark in 80 countries, which means that in these countries, the word Aspirin must be printed with a capital A. Aspirin is a generically used term in Australia and New Zealand. Bayer also held the trademark for heroin, which was trademarked in 1898 as a morphine substitute.