Apollo is a significant technology stack element that many organizations seek in job candidates within the tech industry. It refers to Apollo Client, Apollo Server, and Apollo Graph Manager, software implementations developed by Meteor Software which uses GraphQL specification. These tools ensure effective communication between APIs (Application Programming Interface) and client-side applications by enabling efficient data fetching and error management.

Apollo Client is a comprehensive state management library for JavaScript that enables you to manage both local and remote data with GraphQL, facilitating benefits such as intelligent caching and declarative data fetching. On the other hand, Apollo Server is an open-source, spec-compliant GraphQL server that is compatible with any GraphQL schema, providing features like performance tracing, error tracking, and schema management.

Candidates aspiring to master Apollo should equip themselves with an in-depth understanding of how APIs function. Familiarity with JavaScript and Node.js is crucial, as these are integral to working with Apollo Client and Apollo Server, respectively. Also, understanding the principles of GraphQL - a query language for APIs - is essential for efficient use of Apollo tools. Knowledge in related areas such as SQL, HTTP, and REST APIs can serve as a foundation for learning Apollo.

As companies increasingly shift towards a microservice architecture, the ability to build and manage efficient APIs becomes more crucial. Apollo offers a set of tools to achieve this seamlessly. Thus, mastering Apollo could be a valuable asset for tech enthusiasts, developers, and anyone willing to work optimally in modern web development environments. Professionals certified or experienced in Apollo often carve fulfilling careers as Backend developers, Full-stack developers, and Systems designers, among other roles.