This is an explanation of a feature layer.
A user group is a collection of users that have access to maps and apps in ArcGIS Online usually related to a specific area of interest, project or partner.
Item types describe the categories of items that can be uploaded or created in ArcGIS Online. These include web maps, feature layers, web apps
A polygon is any 2-dimensional shape formed with at least 3 straight lines
An illustrated list of map content: the symbols, type styles and, if appropriate, shading or colors shown on a map or map series, and the meaning of each.
An collection of geographic information from around the world including maps, apps, and data layers provided by Esri to use in various applications
The extent on a map which the user will see when first opens it up on a web browser
A small icon on websites, often in the sidebar, that performs one simple function. For example, a legend widget will allow the user to display or hide the legend on a map
A table that includes all of the data in a feature layer. Each row in the table holds information about a single record/item and each column has information about a specific part of the item (such as name, location, values, etc.)
An Esri app that contains entries called sections, which users can scroll through. Each section has an associated map, image, video or web page
A simple format for storing the geometric location and attribute information of geographic features