Schematic: name.asc the drawing with your circuit (a text file)
Symbol: name.asy symbols for the schematic (a text file)
Netlist: name.net unprocessed netlist (text file viewable from within LTspice
& usable by other SPICE engines)
Logfile: name.log info and results from .four, .measure, .op (text file viewable
from within LTspice); may also contain the fully processed
and expanded netlist (a Control Panel setting)
Result: name.raw binary output data file (text format may be optionally specified)
Result: name.fft binary result of an FFT
Plot settings: name.plt text file used to save and restore Waveform Viewer plot settings
Model file: abc.xyz text file containing model(s) - may be any valid file name
Circuit file: name.cir frequently used extension for an external netlist input file (text)