As a developer, you can use the following:
Developer controls
These allow you to add ArcGIS functionality, such as map, page layout, table of contents, and toolbar controls, as well as provide graphic user interfaces (GUI).
Dynamic display
This provides a mechanism for synchronized refreshing that allows moving objects, such as maps and graphics, to be displayed with fast refresh-rate technology.
Spatial analysis
This supports geoprocessing—including vector, raster, 3D, and network analytics—as well as models, scripts, and tools.
Toolbars
These provide GIS tools, such as Pan, Zoom, Identify, Selection, and Editing, to interact with maps.
Advanced editing functionality
This supports editing tasks such as adding, modifying, and deleting map features like points, lines, and polygons.
Developer tools
The tools in ArcGIS Engine include code projects, wizards, templates, and code snippets that combine with your integrated development environment (IDE) to help you create custom desktop GIS applications.
To learn more about developing with ArcGIS Engine, visit the ArcGIS Engine Resource Center.