I have background of web-applications, enterprise applications. With that context; where do I fit blockchain ! What is it in most simplest terms !
In most simplest terms; to start with think of block-chain as a distributed database.. Probably something like NoSQL...
Just like we have many NoSQL databases; we have many block chain implementations like Ethereum, Ripple, Hyperledger.
Just like we can create infinite applications using NoSQL databases; similarly we can do using blockchain in almost all domains.. BitCoin is just most successful application developed on blockchain. As we know any application can be developed in most technologies; but still every one has pros and cons and more suited for particular use cases .. The target markets for Blockchain are mostly banks and other Financial Institutions.
Best part is that block-chain is NOT just a highly secured, distributed database which is owned by many companies.. but it has many more advanced concepts like Smart Contracts ( something like Serverless pieces of code which can run independently )..
I am not saying this is complete explanation. You can anyway find lots of stuff on internet.. This is to keep thing overly simple ( which causes some of not correct/incomplete info )