There are two types of barometers, Mercury barometers and then Aenroid barometers.
mercury barometers and aneroid barometers both measure air pressure.
Mercury and aneroid barometers.
The two common types of barometers are mercury barometers, which use the height of mercury in a column to measure atmospheric pressure, and aneroid barometers, which utilize a flexible metal membrane to detect and measure pressure changes without using liquid. Digital barometers are also becoming more popular, using electronic sensors to measure pressure.
Many do, but not all. Most barometers that people would have in their homes are aneroid barometers, which don't contain any mercury.
Pilots use barometers to see the air pressure from the plane.
They are more portable and can be used for airplane equipment
Digital barometers, much like analog barometers, are used to forecast the weather using humidity, air pressure, and dew point. This answer needed a few more characters.
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predict weather
Mercury
pilots use barometers because they don't want to crash because of the air pressure might be high