I often get this question a lot and I often find myself over explaining the term and most of the times I get the sense that I wouldn’t have done justice to the topic. In my own words Blockchain technology, which is often referred to by many people as the new internet, is a digital technology which allows digital information to be created and distributed but not copied.
It was originally devised for the purpose of Bitcoin and digital currency today blockchain technology is being used for other purposes too including the formulation of banking aids and tools. From blockchain technology comes cryptocurrency which is a digital currency that works like email for money which can be sent from one wallet to the next.
Still lost ???? Here is a video from the IBM Think Academy explaining this blockchain phenomenon as one would to a five-year old.
Have more time/interest? I recommend this slightly more in depth course on Udemy https://goo.gl/5kmghX_