In Tableau, dimensions and measures are concepts which are used to organise and visual data.
Dimensions are often categorical fields which represent qualitative data or categories which are used to group data. Examples of dimensions include peoples’ names, regions or product types and are made up of data types such as string or geographical data.
Measures, on the other hand, are quantitative or numerical data fields and are the measurements which are used to create charts which visualise numerical data in charts such as line graphs, bar charts or scatter plots.
Fortunately, Tableau separates dimensions and measures by a line with dimensions at the top and measures at the bottom for each dataset.
However, it is difficult to understand dimensions and measures without also understanding the continuous and discrete data.
Discrete data are data types with distinct, finite values and can be represented by bar charts, histograms, or other visualisations with individual categories while continuous data are all values within a given range and can include fractions or values with decimal values. In Tableau, these two data types are differentiated by colour, with discrete values being shown as blue data type icons and continuous data shown with green data type icons.
Many introductory users of Tableau incorrectly assume that dimensions are always discrete data and measures are always continuous data,which is not always the case. There can often be data which are continuous dimensions or discrete measures.
In the example above, the field ‘Year’, ‘Month’ and ‘Date’ fields are considered dimensions in Tableau but have green coloured icons, indicating they are continuous data types, represented by numbers.