Upwork is a leading freelance marketplace connecting businesses with independent professionals in various fields like development, design, marketing, writing, and more. Companies can post job listings and hire freelancers based on their expertise, portfolio, and ratings. Upwork offers project-based contracts, hourly work, and fixed-price engagements, providing flexibility for both employers and freelancers. The platform includes collaboration tools, secure payments, and review systems, making it a go-to choice for outsourcing tasks and projects.