Mood and tone are similar. You might think of tone as the attitude of the author. Mood is the atmosphere or the overall feeling of the written passage. It causes the reader to feel scared, peaceful, or happy.
Probably the easiest mood to recognize and describe is a humorous one. Have you ever read a story and just laughed out loud? The author was able to communicate something funny to you. It may have been a character's actions, words, or just a funny situation.
An author may create a mood of suspense or mystery. Unexplained things may happen. It may be a dark or scary setting. The characters may be acting in a strange, mysterious way.
An author can even combine these two things. The setting may be scary with unexplained things happening, but the way the character acts in that setting could be very humorous.
In a poem called "A Murder in the Garden" by Joyce Furstenau, the author carefully chooses her words to create a scary, suspenseful mood:
I saw it with my own two eyes.
It gave me such a fright!
The tiny little thing was caught.