The Biological Carbon Pump includes all those processes in the ocean that cause photosynthetically formed organic carbon (primary production) by phytoplankton in the sunlit surface layer (the euphotic zone) to be removed from contact with the atmosphere. It is a mechanism that sequesters carbon dioxide (CO2) from contact with the atmosphere for weeks to hundreds or even millions of years (geological time-scales). Together with the physical carbon pump, the biological carbon pump constitutes the ocean's CO2 sink. Combined, these two major processes in the global carbon cycle have removed about 2–2.5 Pg Carbon per year (last decade average). This e-Lecture introduces the biology and biogeochemistry of the Biological Carbon Pump by paying close attention to relevant timescales (from today's carbon cycle to processes on geological time-scales) and to the global carbon cycle. Topics include an introduction to the different carbon pumps (biological, carbonate, and physical), followed by a detailed process-oriented introduction to the biological carbon pumps. This also includes the organismal aspects, such as an introduction to phytoplankton, primary production, distribution of primary producers in the global ocean, and the role of zooplankton in particle formation, transformation, removal, and active transport. We cover specific aspects of the lecture as modules (“Excursions”) that give the reader/lecturer the chance to explore some topics in greater detail. These “Excursions” are entitled “Instrumentation: Quantifying Particle Flux,” “Particle Sinking and Degradation,” and “The Biological Carbon Pump on Geological Timescales.”