Space-based data centers (SBDCs) have moved within a few years from a speculative concept to an emerging industry, driven by the energy and cooling limits of terrestrial infrastructure, the explosion of satellite-generated data, and the falling cost of access to orbit. This thesis maps and interprets that emerging sector. After reviewing the state of the art of terrestrial data centers and the engineering and economic constraints of in-orbit computing, it organizes the field into three archetypes, namely LEO in-orbit edge, cislunar storage (an umbrella for sovereign storage spanning low Earth orbit, the cislunar domain and the lunar surface) and hyperscale orbital, and analyzes forty-five players together with their venture-capital funding, geography and maturity.