> ## Documentation Index > Fetch the complete documentation index at: https://docs.cosmosid.com/llms.txt > Use this file to discover all available pages before exploring further. # Overview > What a stacked bar chart shows about microbial composition, and the exploratory questions it helps you answer. ## What is a stacked bar chart? A stacked bar chart visualizes the microbial composition of samples. Each **bar** is one sample (or one group of samples), and each colored **segment** inside the bar is a microbial feature (a taxon or function), sized by how much it contributes to the profile. For example, if a species fills half of a sample's bar, it accounts for roughly 50% of that sample's microbial profile. ## Why is it useful? Stacked bar charts give a quick, intuitive way to compare taxonomic or functional composition across samples: whether profiles look similar, whether specific taxa dominate certain samples, and whether biological or experimental groups differ. They're especially useful for questions like: * Do treated and control samples have visibly different taxonomic profiles? * Are specific taxa enriched in one disease group? * Do samples from the same body site show similar composition? * Are there dominant taxa that characterize a subgroup of samples? * Is a metadata variable associated with a visible shift in composition? Stacked bar charts are **exploratory**. They reveal visual patterns and generate hypotheses, but they don't test statistical significance on their own. Follow up a visible difference with differential abundance testing, diversity analysis, or a machine-learning model, depending on your question.