The mean composition of ocean ridge basalts (MORB) is determined using a global dataset of major elements, trace elements, and isotopes. The study compiles data from 771 ridge segments, including their mean depth, length, and spreading rate, to calculate average compositions. Segment averages are weighted by length and spreading rate to reduce sampling bias. A bootstrapping technique provides rigorous error estimates. The study proposes a revised nomenclature for MORB: "ALL MORB" represents the total composition of the crust excluding back-arc basins, "N-MORB" is the most likely basalt composition away from hot spots, and "D-MORB" is the depleted end-member. ALL MORB and N-MORB are more enriched than earlier estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher melting and fluid-mobile elements, reflecting water's influence. The study re-evaluates global geochemistry, showing that the K/U ratio is consistent with previous estimates. The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB suggests Earth's mantle may be chondritic or MORB preferentially samples an enriched reservoir. The study provides a comprehensive database of 18,000 words, 13 figures, and 3 tables, offering new insights into MORB composition and Earth's reservoirs. The new nomenclature reflects the global data distribution, with ALL MORB representing the ocean crust reservoir, N-MORB as the most likely basalt composition away from hot spots, and D-MORB as the depleted end-member. The study compares new averages to previous literature values, showing that MORB is more enriched than traditional N-MORB estimates. The methodology, including segment length and spreading rate weighting, provides the most reliable estimate of average MORB to date.The mean composition of ocean ridge basalts (MORB) is determined using a global dataset of major elements, trace elements, and isotopes. The study compiles data from 771 ridge segments, including their mean depth, length, and spreading rate, to calculate average compositions. Segment averages are weighted by length and spreading rate to reduce sampling bias. A bootstrapping technique provides rigorous error estimates. The study proposes a revised nomenclature for MORB: "ALL MORB" represents the total composition of the crust excluding back-arc basins, "N-MORB" is the most likely basalt composition away from hot spots, and "D-MORB" is the depleted end-member. ALL MORB and N-MORB are more enriched than earlier estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher melting and fluid-mobile elements, reflecting water's influence. The study re-evaluates global geochemistry, showing that the K/U ratio is consistent with previous estimates. The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB suggests Earth's mantle may be chondritic or MORB preferentially samples an enriched reservoir. The study provides a comprehensive database of 18,000 words, 13 figures, and 3 tables, offering new insights into MORB composition and Earth's reservoirs. The new nomenclature reflects the global data distribution, with ALL MORB representing the ocean crust reservoir, N-MORB as the most likely basalt composition away from hot spots, and D-MORB as the depleted end-member. The study compares new averages to previous literature values, showing that MORB is more enriched than traditional N-MORB estimates. The methodology, including segment length and spreading rate weighting, provides the most reliable estimate of average MORB to date.