Nozzle temperature
Nozzle temperature is the temperature the hotend heats the nozzle to so the filament melts and flows. Each material needs its own setting.
Why it matters
Too cool and the filament doesn’t melt well, so layers bond poorly. Too hot and it oozes, which causes stringing. Prusa recommends lowering the nozzle temperature by 5 to 10 degrees Celsius to reduce stringing.
Typical settings differ a lot by material. Prusa’s profiles use about 210 to 215 °C for PLA, 230 to 240 °C for PETG and 260 °C for ASA. Polymaker gives a wider printing range of 190 to 230 °C for its PolyLite PLA.
Because brands differ, start with the range printed on the spool or the product page. Your slicer’s filament profile for that brand is usually the safest starting point.
The nozzle temperature works together with the heated bed temperature. Both are part of a filament’s profile, and changing one can mean adjusting the other.
If you are buying a printer, check its maximum nozzle temperature. A hotend that tops out low can’t run materials such as ASA.