What is your simplest explanation of string theory?

I've noticed that none of these answers actually answer the question.

The simplest explanation of string theory I can think of:

Particles we currently consider "point particles" (electrons, quarks, photons, etc.) are actually tiny pieces of string with each a characteristic vibration. They interact in a sort of harmony that results in/manifests as the physical laws we observe.

If anyone with more knowledge in the field can correct me, I ask for improvements. This is just how I personally explain it to people who ask, and I'd hate to give out false information.

String theory is the theory of gravity which starts out by postulating that only things at the boundary of space-time make sense. The local space and time have to be reconstructed from the boundary description. This is called the holographic principle. In the 1960s, a primitive vesion of this idea was called the S-matrix principle.

There are two kinds of boundaries, those far away from everything, called "cosmological" and those which are on top of matter, called "black hole horizons". The description of these two horizons are similar. The oscillations of these boundaries describe the entire space-time nearby.

The detailed form of string theory begins with the postulate that there are black holes that make extended, light, 1 dimensional lines. The vibrations of these black holes then must account for all the particles in the theory, because the vibrations of a black hole encodes anything that can fall through.