With PLA filament, if you print at too high of a temperature, the PLA will curl slightly when it cools along the edges, which might pull the edges up off the build plate over time. If you’re using Polar 3D filament, we recommend 185° C on a Polar3D printer, or 220° C on a FlashForge Inventor II printer. PLA filament from other manufacturers may need to be printed at a slightly different temperature; check any information from the manufacturer of the filament. (However, note that filament manufacturers are likely to tell you the temperature at which the filament should be extruded; but what you need to know is what operational temperature to set for your printer’s extruder, which may not be the same thing!)
Note that ABS filament is quite prone to curling as it cools, which is one reason why we don’t recommend ABS filament for beginners; PLA filament is much more forgiving (if printing at the proper temperature).