Explore the Interfaces.jl package for defining and testing object interfaces in Julia through this 10-minute conference talk by Rafael Schouten and Guillaume Dalle. Learn about the package's approach to addressing Julia's lack of built-in strict interface definitions, including its use of named tuples of functions and mechanisms for optional interface components. Discover how Interfaces.jl enforces both run-time and compile-time constraints, provides traits for other packages to check, and allows for easy verification of interface implementations during testing or package precompilation. Gain insights into programmatically testing interface implementations across multiple packages with a single command, and understand the package's role in improving Julia's package interoperability.