Rational Unified Process

What exactly is the Rational Unified Process, or RUP as many call it now? I can give several answers to this question, from different perspectives: 

• What is the purpose of the RUP?
It is a software engineering process, aimed at guiding software development organizations in their endeavors.

• How is the RUP designed and delivered?
It is a process product, designed like any software product, and integrated with the Rational suites of software development tools.

• What is the structure of the RUP; how is it organized internally?
The RUP has a very well-defined and regular structure, using an object-oriented approach for its description.

• How would an organization proceed to adopt the RUP?
The RUP is a process framework that allows a software development organization to tailor or extend the RUP to match its specific needs.

• What will I find in the RUP?
It captures many of modern software development's best practices harvested by Rational over the years, in a form suitable for a wide range of projects and organizations.