I was studying about mechanical energy and I found a line in my book saying that negative value of mechanical energy indicates a bound state. The examples given were electron in an atom, satellite revolving around a planet both are in bound state having negative mechanical energy.
Since I wasn't aware of bound state I searched it on google where I found that "In quantum physics, a bound state describes a system where a particle is subject to a potential such that the particle has a tendency to remain localised in one or more regions of space. The potential may be either an external potential, or may be the result of the presence of another particle"**(CREDIT-WIKIPEDIA)**but throughout the article,i never found terms like negative mechanical energy r satellite revolving around earth.
So the Wiki article made it more confusing for me. I'm stuck here. Shall be obliged if someone help me. I have a little knowledge of Quantum mechanics and a bit more of classical mechanics, so if you are writing an answer, please try to keep it simple.