Text becomes unreadable
On the very first line, type in "dont eat the donut" (without quotes) then save and close the file. Note: the file should have only one line of the text above.
Now, open the same file. You'll notice the text becomes unreadable squares. (try this with different text with the same format and length).
Create a log
On the very first line, type in ".LOG" (without quotes) then press Enter for a new line
Now you can type in some text if you want, then save the file.
Next time when you open the file, notice its contents. Notepad automatically adds a time/date log everytime you open the file.