Clinical bioinformaticians play a critical role in clinical molecular diagnostics laboratories as developers of data analysis pipelines, tools, and databases. They also contribute to a variety of other tasks, such as genomic data interpretation, database administration, hardware engineering, informatics, information technology, infrastructure support, and software engineering. To effectively perform these functions, the clinical bioinformaticians must possess a strong foundational knowledge of molecular biology, genetics, genomics, computational biology, and the relevant federal, state, and/or regional regulations, laboratory accreditation requirements, and other standards and best practices. This first article in the Association for Molecular Pathology's Clinical Bioinformatician Body of Knowledge series provides a comprehensive core knowledge base on molecular biology, genetics, genomics, clinical laboratory practices, sequencing technologies, databases, and clinical applications. This resource serves not only to equip clinical bioinformaticians for their professional roles but also as a valuable reference for laboratorians.