Bitcoin is a decentralized blockchain technology that can be used as a digital currency and hold value in the market. It allows to make safe and secure transactions from one address in the blockchain to another without any loss of information or danger to be corrupted on the way to the destination. The only way someone can access the data in your bitcoin wallet is if you by not being careful give out your private key to your wallet. Otherwise you are rock solid.
Below is a video explaining the technology in a more friendly way. Also you can visit Bitcoin.org and find out more:
Link to the Bitcoin Website: https://bitcoin.org/en/