A rain gauge is used to capture and measure rainfall. It's usually in the shape of tube with a funnel at the top what collects the rain water, and can measured by a device or is read manually that determines the amount of rainfall. This device comes in a range of shapes and sizes is calibrated to collect rain in either inches or millimeters. 

The funnel shaped at the top of device is used the capture the most amount of rain. The water then flows into the tube where upon it is measured by markings. 

A rain gauge is a useful tool for a variety of reasons. It provides important information about the weather, including the amount of rainfall, the intensity of the rainfall, and the duration of the rainfall. This information can be used to make informed decisions about water management, agricultural practices, and flood prevention. For example, farmers can use rainfall data to determine when to plant crops and how much water their crops need. Water management authorities can use rainfall data to plan for water storage and distribution. Homeowners can use rainfall data to determine if their lawns and gardens are getting enough water or if they need to supplement with irrigation.

A rain gauge is a simple but essential tool for monitoring rainfall in a particular area. It provides valuable information about the weather, which can be used to make informed decisions about water management, agricultural practices, and flood prevention. Whether you are a farmer, gardener, or meteorologist, a rain gauge is a valuable investment that can help you make the most of your resources and protect your property.