safaa, A limb is a large branch of a tree. When you go "out on a limb", you put yourself in a dangerous position. The branch becomes smaller and smaller the farther out you go, and eventually, you get to the point where any movement backward or forward will cause the branch to sway and possibly break. John went out on a limb when he decided to speak out against waste in county government. Speaking out against the county government put John in a dangerous position. Why? Here are two possible reasons: A) If he works for the county he might be fired or punished by his superiors for his statements. B) Perhaps John is partly responsible for the waste in government, and his speaking out against it will put him at risk. Either way, he would be out on a limb.

It doesn't mean "to be in big trouble," or "to be in a difficult situation." Denis is entirely correct: it means to put yourself in a dangerous (exposed) position. Also, "to go out on a limb" is generally done for someone; or to serve higher (nobler) purpose. "He really went out on a limb there, speaking out for her the way he did." You can't really use it when you simply put yourself in danger. Like if you're into hazardous sports, such as rifting, for instance, you wouldn't say: "I went out on a limb when my car almost tipped over." It's not grammatically incorrect, but simply not used that way. However, you would say, "He went out on a limb, trying to prevent his friend's car from tipping over."

My dictionary says "to be alone and without help or support" Also "go out on a limb" means "to take a risk"

howdy! In a difficult, awkward, or vulnerable position, as in I lodged a complaint about low salaries, but the people who had supported me left me out on a limb. This expression alludes to an animal climbing out on the limb of a tree and then being afraid or unable to retreat. Late 1800s cowboy...

"out on a limb" means: " to be in danger" , " to be in big trouble"