If you have been using the same keyboard for a number of years then you will notice that a good number of keys are filthy. One option is to scrub away with a cloth which is what I do, or the new way is to buy a green blob called Cyber Clean. The green blob can clean keyboards, iPhones, laptops, printers and anything else electrical.
To get it to work you just squidge the blob around and it’s tacky surface sucks up the dirt and holds it in there forever. The Cyber Clean blob will clean several times and once full of dirt it will need to be replaced as the blob is unforgiving and will never release the dirt particles it sucks up. Check out the video below for a demonstration