Neutrinos are one of the elementary particles(think of it as "basic ingredients for atoms") and also one of the least understood of them. They don't carry electric charge-they're electrically neutral, so it doesn't get attracted to electromagnetic forces. It's also very light(less than one-10,000,000 the weight of an electron), though we don't know the exact weight yet. These properties make the neutrino pass long distances close to light speed, without being affected by the environment around it. In fact, they can easily pass through objects- millions of neutrons, mostly from the sun, are zapping right through your body even as I type this and as you read this.
If it's night where you live right now, then the neutrinos that pass through you have already passed through the Earth itself. But you don't feel any pain from it, thank god.
That proves how "ghostly" neutrinos are.