Matplotlib

This is the plotting library you'll use for pretty much any data visualization in Python. The skill covers both the pyplot interface and the object-oriented API, though it strongly recommends the latter for anything beyond quick exploration. You get clear guidance on the full range of plot types (line, scatter, bar, heatmaps, 3D), subplot layouts including the flexible mosaic approach, and exporting at the right DPI for your target medium. The styling section is practical, covering colormaps, rcParams, and annotations. If you're making charts in Python, whether for notebooks, papers, or dashboards, you're probably using matplotlib, and this gives you the patterns to do it cleanly.