In the field of computer science, data is considered as the main raw material which is produced by abstracting the world into categories, measures and other representational forms (e.g., characters, numbers, relations, sounds, images, electronic waves) that constitute the building blocks from which information and knowledge are created. Big data has commonly been characterized by the defining 3V's properties which refer to huge in Volume, consisting of terabytes or petabytes of data; high in Velocity, being created in or near real time; and diversity in Variety of type, being structured and unstructured in nature. The main purpose of the Encyclopedia of Big Data Technologies is to provide IT professionals, educators, researchers and students with a comprehensive set of definitions covering the most relevant Big Data technologies. Table of Contents -- chapter titles and authors -- will be available as work progresses. General announcements, messages for editors and authors, and progress status checklists also will be posted here.