For questions related to the QFN (quad-flat no-leads) component package.

QFN (quad-flat no-leads) devices have a rectangular package with contact pads along each edge that do not extend out past the edge of the package. Advantages include a smaller physical size and reduced lead inductance at the cost of them being more difficult to hand-solder and rework. The Wikipedia page Quad Flat No-leads package has more information and shows a typical QFN package:

QFN package

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