I sing a lot of karaoke, but I'm not a trained singer. One time, I was sitting with a guy who actually used to be a professional back-up singer in Nashville. He listened to me sing a few songs and then offered me some free advice. That was the first time I ever heard the term "chest voice" in a sentence. He said I had plenty of power in my voice, but I needed to recognize when to shift from my chest voice to my middle and head voices.
He did a few songs to demonstrate the difference, and I was amazed at how good he was. He did a song by Roy Orbison that started really low in his chest voice and then end on a really high falsetto note in his head voice. Every time I tried that same song, I couldn't hit the high notes without running out of breath. He told me that a lot of amateur singers tend to stay in chest voice too long, and they can't support the higher notes very well from there.