Hi there!

Is there a difference between 'somebody' and 'anybody'?
Like you can use it only in a particular situation?

The reason I ask this is because I've just saw a movie (only a fragment at youtube, the lion king) where Simba was calling for help:

Thanks in advance Emotion: smile.
Ah! A birdwatcher! Welcome to English Forums.

Yes, somebody is usually used in affirmative statements (Somebody loves sparrows) while anybody appears more often in questions and negative statements (Doesn't anybody love sparrows? I don't think anybody does.) These guidelines are not absolute, however.

In your example:

"somebody?" -- the speaker hopes that there must be someone within hearing distance (speaker presumes there is somebody)
"anybody?" -- the speaker is losing hope that anybody at all is within hearing distance (speaker no longer presumes there is somebody)
Perfect anwser! This is useful Emotion: smile.
So you can't really call it a "rule", it's more of a guideline.

Thank you very much.