What does your print look like?
Tap the picture that matches. You get the causes in the order that actually fixes them — with the exact setting to change and where to find it in your slicer.
Every problem, in detail
Thin plastic whiskers strung between separate parts of the model.
The print peels off the bed, or the first layer never bonds and turns into spaghetti.
Corners curl up off the bed and the bottom of the print is no longer flat.
Thin, patchy or missing lines; walls with gaps between them; weak brittle parts.
The print suddenly steps sideways part-way up and everything above is offset.
The bottom one or two layers bulge outwards, so the base is wider than the rest.
Ripples or echoes on the surface just after a corner or a sharp feature.
Layers split apart, usually part-way up a tall print, and the part snaps along a layer line.
Small bumps or pimples scattered on the outer wall, often lined up in a vertical seam.
The top surface has bumps, gaps or open holes instead of coming out flat and solid.
Walls look fat and bumpy, dimensions come out oversized, and the nozzle drags through excess plastic.
Extruder clicks or skips, extrusion stops mid-print, or nothing comes out at all.
Starting temperatures, bed, cooling and retraction for every common filament.
Why this exists
Search any print defect and you get forum threads where twelve people guess, a video that takes nine minutes to say "dry your filament", and a manufacturer's blog post that recommends the manufacturer's filament. All of it stops at advice like "reduce your retraction" — which is not actionable, because the setting is called something different in every slicer and the right value depends on whether your extruder is direct drive.
So every fix here names the setting, the menu path, and a starting value. And they are ordered by what actually resolves the problem most often, not by what is easiest to write about. Moisture is listed before retraction on the stringing page because moisture is more often the real cause, even though every thread starts with retraction.