Word count is a very common tools that used to calculate number of lines, words and characters. For example if I can do this
echo "hello world." | wc
1 2 13
The result indicate that there are 1 line, 2 words and 13 characters.
You can output result separately, -c indicates characters, -w indicate words, -l indicate lines.
echo "hello world." | wc -c
You can count for any file even binaries by using -c
cat hello.c | wc -c
Try to check with ls -l hello.c, you will discover that, the characters count is actualy same as the bytes of the files.
cat `which cat` | wc -c
is actually returns file size of cat binaries in terms of number of bytes.