What was the zkSync era?

Could you elaborate on the era known as zkSync? What significant milestones or achievements did it mark in the world of cryptocurrency and finance? How did it revolutionize the way transactions were processed and secured? Did it pave the way for new advancements in the field, or was it more of a stepping stone towards greater innovations yet to come? Understanding the context and implications of the zksync era is crucial in appreciating the evolution of this dynamic and ever-evolving landscape.