Back in the "good" old days, most cameras had very crude light meters, if they had light meters at all. I remember owning a Russian Zenit-E 35mm SLR camera in the 1970s that had a simple selenium photocell mounted outside the camera on the front of the pentaprism, with a moving needle in the viewfinder but no actual link to the exposure controls, which were fully manual. It was a light meter of sorts, but it was a bit hit-or-miss and would be utterly defeated by shooting into the sun or other bright lights. The only way to get a good photo out of it was to take a light reading and then guess. It was certainly more of an art than a science.
These days things are very different. Even the cheapest digital cameras offer sophisticated metering systems featuring through-the-lens centre-weighted metering, multi-zone evaluative metering, and even spot metering. There should really be no excuse for a badly-exposed photograph anymore, but the trouble is that most people don't know how to make the best use of these advanced features, and usually just leave their cameras set on the default multi-zone mode. Let's see if we can't do something about that, by explaining how to use least-understood but most creatively useful of these features, spot metering.
You'll usually find the spot metering option in your camera's menu under Metering Mode. It normally appears alongside Evaluative (multi-zone) and Centre-Weighted metering, and is identified by an icon of a rectangular box with a round dot in the middle. On some DSLR cameras the metering mode will have its own external control, while on many compact cameras it is also found in the function menu.