Google Analytics

Dimensions: Describe Data

A dimension is an descriptive attribute or characteristic of an object that can be given different values. For example, a geographic location could have dimensions called Latitude, Longitude, or City Name.
You can organize, segment, and analyze your data. In some reports, you can add and remove dimensions to see different aspects of your data.

Metrics: Measure Data

Metrics are individual elements of a dimension that can be measured as a sum or a ratio. For example, the dimension City can be associated with a metrics like Population, which would have a sum value of all the residents of the specific city.
Page per Visit, and Average Visit Duration are examples of metrics in Google Analytics.

Relationship between dimensions and metrics

Although dimensions and metrics can stand alone, they usually are used in conjunction with one another. The values of dimensions and metrics and the relationships between those values is what creates meaning in your data. For the greatest insights, dimensions are often associated with one or more metric.