The paper presents a comprehensive estimate of the global budget of baryons in all states, with conservative uncertainties. Most baryons today are in the form of ionized gas, contributing a mean density uncertain by about four times. Stars and their remnants make up about 17% of the baryons by mass, while populations contributing most of the blue starlight account for less than 5%. The formation of galaxies and stars appears to be an inefficient process. The sum of the baryon budget, expressed as a fraction of the critical Einstein-de Sitter density, ranges from 0.007 to 0.041, with a best guess of ΩB ≃ 0.021 (at Hubble constant 70 km s−1 Mpc−1). This agreement with the prediction from light element production and intergalactic plasma density at redshift z ≃ 3 suggests a near-complete survey of major baryonic states. The paper details the baryon budget at low redshift, comparing it to observations at higher redshift and constraints from light element production. It discusses the contributions from stars and remnants in galaxies, atomic and molecular gas, clusters of galaxies, and groups of galaxies. The budget includes uncertainties in the mass-to-light ratios of different stellar populations and the density of plasma in voids and low surface brightness galaxies. The paper also explores the possibility of uncounted components, such as massive compact halo objects (MACHOs) and brown dwarfs. At redshift z ≃ 3, the budget is constrained by quasar absorption line spectra, with the dominant component being the Lyman-$\alpha$ forest gas. The paper concludes with a discussion of nucleosynthesis constraints on the baryon density, emphasizing the importance of helium and deuterium abundances.The paper presents a comprehensive estimate of the global budget of baryons in all states, with conservative uncertainties. Most baryons today are in the form of ionized gas, contributing a mean density uncertain by about four times. Stars and their remnants make up about 17% of the baryons by mass, while populations contributing most of the blue starlight account for less than 5%. The formation of galaxies and stars appears to be an inefficient process. The sum of the baryon budget, expressed as a fraction of the critical Einstein-de Sitter density, ranges from 0.007 to 0.041, with a best guess of ΩB ≃ 0.021 (at Hubble constant 70 km s−1 Mpc−1). This agreement with the prediction from light element production and intergalactic plasma density at redshift z ≃ 3 suggests a near-complete survey of major baryonic states. The paper details the baryon budget at low redshift, comparing it to observations at higher redshift and constraints from light element production. It discusses the contributions from stars and remnants in galaxies, atomic and molecular gas, clusters of galaxies, and groups of galaxies. The budget includes uncertainties in the mass-to-light ratios of different stellar populations and the density of plasma in voids and low surface brightness galaxies. The paper also explores the possibility of uncounted components, such as massive compact halo objects (MACHOs) and brown dwarfs. At redshift z ≃ 3, the budget is constrained by quasar absorption line spectra, with the dominant component being the Lyman-$\alpha$ forest gas. The paper concludes with a discussion of nucleosynthesis constraints on the baryon density, emphasizing the importance of helium and deuterium abundances.