<p>The BETA programming language is a modern language in the SIMULA 67 tradition. It supports the object-oriented perspective on programming and contains comprehensive facilities for procedural and functional programming. BETA replaces classes, procedures, functions and types by a single abstraction mechanism called the <em>pattern</em>. Patterns may be organized in a classification hierarchy by means of <em>sub-patterns</em>. The notion of virtual procedure is generalized to virtual pattern. Virtual patterns combined with sub-patterns make it possible to delay the specification of an attribute in a pattern. Attributes may then have different bindings in different sub-patterns. BETA also provides a unified framework for sequential, coroutine and concurrent execution.</p><p>This paper is a tutorial introduction to BETA.</p>