The technology that makes blockchain a reality is a complex set of inventions working together to achieve the common goal of a global source of agreements. To understand how they all tie together, it's good to break the technology down into four main pieces so that we can see the layers where all the decentralized applications run:
What makes Ethereum possible is a set of tools and protocols that are widely used in the community. You'll be able to use those tools for personal projects whenever you want to implement advanced mechanisms that would be very hard to recreate from scratch.
