On 12 January 2020, Taal volcano, Philippines, erupted after 43 years of repose, affecting more than 500,000 people. Using interferometric synthetic aperture radar (InSAR) data, we present the complete pre- to post-eruption analyses of the deformation of Taal. We find that: 1) prior to eruption, the volcano experienced long-term deflation followed by short-term inflation, reflecting the depressurization-pressurization of its ~5 km depth magma reservoir; 2) during the eruption, the magma reservoir lost a volume of 0.531 +/- 0.004 km^3 while a 0.643 +/- 0.001 km^3 lateral dike was emplaced; and 3) post-eruption analyses reveal that the magma reservoir started recovery approximately 3 weeks after the main eruptive phase. We propose a conceptual analysis explaining the eruption and address why, despite the large volume of magma emplaced, the dike remained at depth. We also report the unique and significant contribution of InSAR data during the peak of the crisis.