Logtalk is a declarative object-oriented logic programming language that extends and leverages the Prolog language with modern code encapsulation and code reuse mechanisms while also providing improved predicate semantics. Implemented as a transcompiler in highly portable, extensively tested, and well-documented code, it can use most modern and standards-compliant Prolog implementations as a backend compiler. As a multi-paradigm language, it includes support for modules, prototypes, classes, protocols (interfaces), categories (components and hot patching), event-driven programming, and high-level multi-threading programming (on selected backends).