wc [-lwc] filename...
The default is to use all three flags:
With linux the l, w and c flags may be replaced with the lines, words and bytes longflags, respectively.
Here is an example:
prompt> wc course.tex course.aux 810 4137 27849 course.tex 51 200 5095 course.aux 861 4337 32944 total
The first field is the line count, the second field is the word count, the third field is the character count (size of the file) and the last field is the name of the file (only if more than one file is used).