Voice interfaces are confusing. Alexa, Siri, Cortana, and Google Now all want you to speak to them to get stuff done, but unlike with visual interfaces, there's no obvious way of knowing what it is you can ask. Well, that problem has now been solved for Google at least, with this handy directory of everything you can ask the company's voice interface.

The site is the creation of coder Kristijan Ristovski, who said he was "annoyed" by having to keep up with the ever changing list of Google Now commands. He says that his research turned up more than 150 commands and more than 1,000 variations. "I'll try to keep [the site] up to date," writes Ristovski, adding that he plans to update the directory so the community can add commands.

The site spans a number of categories, from asking about people ("How old is Avril Lavigne?," "Where was Madonna born?") to fiddling with your device's settings ("Turn on the flashlight," "Turn the volume to 2"), and finding information about flights ("Has LH 210 landed?") and movies ("Best movies of 2012"). There's also a section for Easter eggs, including the commands: "Do a barrel roll," "What's the loneliest number?" and "Okay Jarvis." (Try them out yourself!)

The companies creating voice interfaces seem to be aware of these limitations (just this week Amazon made it easier to turn on Alexa skills just by asking), but it remains a central problem for digital assistants. Perhaps Ristovski will expand his directory in future, adding a list of commands for Siri, Cortana, and Alexa too? If only there were some clever, AI-powered digital assistant to take care of such a rote task for us.

SIRI VS. ALEXA COMPARISON