This study presents the largest human microbiota time series analysis to date, covering two individuals at four body sites over 396 timepoints. The research highlights significant variability in an individual's microbiota across months, weeks, and even days, despite stable differences between body sites and individuals. Only a small fraction of taxa are consistently present across all time points, suggesting no high-abundance core microbiome exists. Instead, many more taxa appear persistent but non-permanent community members. The study demonstrates the feasibility of high-resolution assessments of temporal variations in the human microbiome, which will aid in defining normal variation and pathologic states, and evaluating therapeutic interventions. Advances in sequencing and computational technologies, including cloud computing, have enabled this dense time series analysis, paving the way for more precise understanding of microbial community dynamics and their implications for health and disease.This study presents the largest human microbiota time series analysis to date, covering two individuals at four body sites over 396 timepoints. The research highlights significant variability in an individual's microbiota across months, weeks, and even days, despite stable differences between body sites and individuals. Only a small fraction of taxa are consistently present across all time points, suggesting no high-abundance core microbiome exists. Instead, many more taxa appear persistent but non-permanent community members. The study demonstrates the feasibility of high-resolution assessments of temporal variations in the human microbiome, which will aid in defining normal variation and pathologic states, and evaluating therapeutic interventions. Advances in sequencing and computational technologies, including cloud computing, have enabled this dense time series analysis, paving the way for more precise understanding of microbial community dynamics and their implications for health and disease.