In ArcGIS, layers are collections of geographic data. Layers reference a data source, and if ArcGIS AllSource interprets data as spatial, the data's properties and attributes specify how the layer draws on a map, scene, or layout. Data gathered in a layer is represented with points, lines, shapes (polygons), or surfaces. You then use symbols, text, graphics, and images to visualize the data.
Some layers are automatically added to maps when you create the map. Most of the time, however, you manually add layers to a map. Most maps, scenes, and layouts are assembled with multiple layers. The layers are displayed in a particular order, called the drawing order, which is shown in the map's Contents pane. Layers listed at the bottom appear first but always draw below the layers above them.
Once layers are added to a map or scene, you can change how a layer is symbolized, labeled, scaled, and arranged. You can use spatial analysis tools on layers to study the data's characteristics, filter layers using queries or display filters, and extrude layer features into 3D.
Layers are reusable and flexible. For example, you can use the same imagery layer in every map you create. If the location of the data changes, however, the data source path must be updated.
Types of layers
There are many different types of data that are represented in ArcGIS AllSource as layers. Layers typically comprise vector (feature) or raster data. The type of layer depends on the type of data you have, its underlying structure, and some other variables.
To determine the layer type, click it in the Contents pane. The layer type contextual tab set appears in the ribbon.
Feature layers
Feature layers represent geographic objects as vectors and can be symbolized in a variety of ways depending on their attribution. Feature layer data references feature classes, which are stored in geodatabases.
Because they comprise vectors, the features can be symbolized with the same symbol or with unique symbols based on values from one or more attribute fields. In the case of quantitative data, commonly used for thematic mapping, a layer can be represented with defined classification ranges. Further symbology options include representing features as proportional symbols, charts, or dot density maps.
There are other types of feature layers, such as stream layers, map notes layers, and aggregated feature layers, that bin or cluster features and map the results based on their attributes.
Raster layers
Raster layers reference rasters or images as their data source. They can be visualized as a single raster dataset or as a mosaic layer that references a mosaic dataset that manages large collections of raster data. A variety of display types are available for visualizing raster data, depending on the raster band count, the presence of a color map, and whether the raster represents unique value data. As with vector layers, rasters can be classified using a variety of standard classification techniques. A variety of image analysis capabilities are available for performing visual analysis of rasters, including processing functions.
Scene layers
If the layer has a three-dimensional aspect, it may be used to create a scene layer. Scene layers are cached to optimize the display of 3D data, and the cache is created as part of a scene layer package. For example, a building scene layer may reference data from feature classes to render the model of a building. Depending on the type of data, scene layers can be queried, symbolized, labeled and edited.
Service layers
Maps and scenes can contain layers that reference map, feature, tile, vector tile and OGC services. The majority of service types either have prerendered content or render the content on the server side. Map service layers can be enabled to support dynamic server-side updates. Feature services allow vector features to be drawn on the client side with the full set of ArcGIS symbology. A stream layer references real-time observations and draws the changes.
Other layer types
Most layers are one of the above types. Because GIS data varies in organization and complexity, there are many more types. For example, a group layer refers to a collection of layers. Some other common types of layers include:
- Query layer—Uses SQL queries to access and reference spatial and nonspatial database tables
- Selection layer—References a subset of features from an existing layer
- Subtype layer—Symbolizes a subtype in a feature class or feature service, as part of a subtype group layer
- Voxel layer—A type of 3D grid-based layer for displaying spatiotemporal data
- Graphics layer—Represents geographic objects but does not reference a dataset
Manage layers
Layers are managed from the Contents pane. You can turn layer drawing on and off from there, reorder them, and group them as needed.
Manage layers in scenes
Maps draw layers in 2D. Scenes draw both 2D and 3D layers and are organized into 2D and 3D layers in the Contents pane. To move a layer from one category to another, click the layer name in the Contents pane and drag it into the other category. If the scene includes KML data, a KML category is also listed.
In scenes, the layers in the 2D Layers category are drawn as though draped over a surface. Symbols in 2D layers are drawn and configured in a two-dimensional context.
Layers in the 3D Layers category have additional capabilities, such as vertical extrusion. Symbols in 3D layers are drawn and configured with three-dimensional properties. When a layer is in 3D, it renders its geometry separately from the rest of the scene. This means that polygons can flicker or stitch with other content in the scene. This display conflict is especially common with ground surface meshes, which are always changing to reflect the best level of detail for the current view location.
You can improve the display of the polygons by extruding the layer to create volumes or changing the depth priority to separate (vertically) the polygons from other content.
Navigate and interact with layers
Explore layers in a map by panning around them to see different areas and zooming in and out to see those areas at different scales. To learn how to navigate a map, see Keyboard shortcuts for navigation. If you're comparing two or more maps, you can link two or more open maps together so they stay in sync as you navigate. You can also explore layers by measuring distances and areas or by viewing the data through time or other variable ranges.
To view the ways you can interact with a layer, right-click its name in the Contents pane. The context menu includes a variety of tools and options for your layer. For example, you can create a selection layer from a selection of features to work on only those features in a separate layer. You can also click the tabs in the Contents pane to list layers according to various properties, and check or uncheck the check boxes to control their properties.
Set layer properties
In addition to interacting with the layer, layer management involves setting layer properties. For example, if the layer's dataset contains information about the time the data was recorded, the layer can be enabled to use time-based data, which allows you to change the way the layer draws. Right-click a layer in the Contents pane
and click Properties 
to view the Layer Properties dialog box.
Legacy:
Some properties in ArcMap, such as symbology and labeling, are set in the Layer Properties dialog box. In ArcGIS AllSource, depending on the type of layer, you can find these and other properties from the ribbon.
Other properties, such as specifying the coordinate system and layer clipping, are properties of the map, not of layers. To access these properties, right-click the map in the Contents pane and click Properties 
.
Work with layer attributes
Layers may reference spatial and nonspatial information in tables, called attributes. For those layer types, you can view and work with attributes in the layer's attribute table. To open the attribute table, on the layer's contextual Data tab, in the Table group, click Attribute Table 
.
In the attribute table, you can select and review data, find features on the map, and edit attribute values. Click the table window's options menu to search records, add joins or relates, and export the table. When you select one or more records in the table they are selected on the map and vice versa.
Not all information in the layer can be visualized through labels and symbology at one time. To discover additional attribution, you can configure pop-ups to display information about features as they are interactively queried. ArcGIS AllSource uses the same pop-up style as other ArcGIS applications, so maps can be designed for presenting information before sharing and publishing them.
Share layers
A layer
can be saved as a layer file (.lyrx) or saved with its data as a layer package (.lpkx) and shared with other members of your organization. To save a layer file, on the Share tab, in the Save As group, click Layer File 
. To save a layer package, in the Package group, click Layer 
. When you add
the layer file or package to another map, it draws exactly as it was
saved.
When layers are shared to the web, they are called web layers. If the data source is accessible, you can publish and share most layer types to your organization's portal as web layers. To share your data as a web layer, in the Share As group, click Web Layer 
. To learn more about web layers, see Introduction to sharing web layers.
Note:
Layer files and packages created in ArcGIS Desktop have .lyr and .lpk extensions, respectively. These files can be read in ArcGIS AllSource, but you cannot save the layer with the .lyr or .lpk extension.Common layer tasks
The following table lists common operations for using layers in ArcGIS AllSource:
| Common task | Additional information |
|---|---|
Add a layer to ArcGIS AllSource | |
Reference other data to a layer | |
Symbolize a layer | |
Label a layer | |
Group layers together | |
Create and edit layer features | |
Work with a layer's attribute table | |
Query and filter a layer's data | |
Change a layer's projection | |
Work with a layer in 3D |