Is it a bird? Is it a plane? No? Maybe it’s the International Space Station.
Nasa’s Spot the Station website will let you know when you can expect to see the Space Station (ISS) in your area and gives you tips on how to identify it. It also has some beautiful images taken on the ISS which are well worth a look.
Are the skies near you too cloudy to see anything? Stellarium is an open source programme that allows you to see the stars as if there is no interference from clouds, light or even the atmosphere.