ArcObjects is the core platform of software components used to build and extend the ArcGIS family of products that includes the ArcGIS Desktop applications, ArcGIS Engine, and ArcGIS Server.

This area of the EDN Documentation Library focuses on ArcObjects-based development. Here you'll find the ArcObjects API reference library, object model diagrams, technical documents, and conceptual materials related to version 9.1.

Use the table of contents on the left to navigate the Help system.

ArcGIS Developer Online and ArcObjects Online are archived sites for developers using versions 9.0 and 8x of ArcObjects.
Code Exchange—find ESRI code samples and user contributed samples and scripts.
Downloads—place for tools, utilities, and add-ins.

Extending ArcObjects
This book helps you to understand how to create components for the ArcObjects platform.

What's New at 9.1
Discusses differences between version 9.0 and 9.1 of the ArcObjects Developer platform. At 9.1, some new functionality added to the ArcGIS platform has resulted in new libraries being added within the ArcGIS Engine and ArcGIS Desktop products.

Migrating to 9.1
Discusses the changes in the ArcObjects class libraries between 9.0 and 9.1 and provides some helpful hints on converting your projects.
Type Changes
Lists type changes between 9.0 and 9.1.