About creating web GIS applications
As you learn and use ArcGIS for Server, you'll probably reach the point where you want to build or customize your own web application to work with your GIS services. Esri offers several resources that you can use to create web GIS applications and services. The resource that you choose depends on your experience and skill level, as well as the requirements of the application.
Intelligent web maps and ArcGIS.com
If you have no prior experience with web application development, consider using ArcGIS.com to make and share a map on the web. ArcGIS.com allows you to make your own web map by adding GIS services from different sources. These could be your own services or services that you discover using ArcGIS.com's search capabilities. You can even make a map from a spreadsheet that you've saved in a CSV (comma-separated value) format.
Using ArcGIS.com, you can make your web maps intelligent. You can choose to define popup information that helps people interact with and learn from your map. Because your map is connecting to live web services, it updates itself whenever the service is updated.
When you've finished making your map, you can save it in ArcGIS Online, an Esri-hosted repository of maps and apps. Intelligent web maps saved in ArcGIS Online are versatile: you can link to them directly, or embed them in future applications that you build with the ArcGIS web APIs and viewers, described later in this topic. In addition to just storing your map on ArcGIS Online, you can create groups to collaborate and share with different user communities.
ArcGIS Explorer Online is a similar application that you can use to make and share maps on the web. Using ArcGIS Explorer Online, you can create geographic slide show presentations that tell a story with your maps. You can save, view, and mark up maps from ArcGIS Online.
If your organization doesn't have a connection to the Internet or wants to maintain its own repository of web maps and apps, you could use Portal for ArcGIS. The portal can be installed locally and provides the same mapping, sharing, and searching functionality as ArcGIS Online, ArcGIS Explorer Online, and ArcGIS.com. The ArcGIS web APIs and viewers can reference web maps stored in your portal.
For full instructions on how to create a web application using ArcGIS.com, see the topic Sharing your map in a web application. Additionally, the ArcGIS.com help provides instructions on how to reference your GIS services on the website, add them to the ArcGIS.com map viewer and ArcGIS Explorer Online, and share them with others.
Configurable web applications
The ArcGIS Viewer for Flex and ArcGIS Viewer for Silverlight are ready-to-deploy configurable web applications, designed for those who have no programming experience. Using these viewers, you can quickly create web apps that reference intelligent web maps from ArcGIS Online or your own portal. If you don't want to embed an entire map, you can embed GIS services individually.
The viewers are designed so that you don't have to write any Flex or Silverlight code. They are fully documented and provide concepts, samples, and forums to help you get started. Experienced developers can extend the viewers using the ArcGIS web APIs.
To learn more about the viewers, see their individual Resource Center pages:
Web APIs
Esri offers web mapping APIs for JavaScript, Flex, and Silverlight. You can use these APIs to build a web application from scratch. They offer common GIS functionality and are designed to be accessible to beginning programmers. The links below contain summaries of the APIs, which in turn link to the ArcGIS Resource Center where you can read the full documentation:
Using the web APIs, you can reference the intelligent web maps that you save in ArcGIS Online (or your own Portal for ArcGIS). This allows you to do your map authoring in the user-friendly environment of ArcGIS.com before you start writing code. Alternatively, you can use the APIs build a map piece by piece from different GIS services, adding or removing them in response to events.
Choosing an API
The APIs are functionally very similar, and when choosing an API, the most important question is not "What do you want to do?", but, rather, "Which platform are your developers most comfortable with?" If you've been working with Microsoft technologies and your developers are inclined in that direction, the ArcGIS API for Silverlight may be a good choice for you. Using similar logic, if you have a lot of past experience writing custom scripts for your ArcIMS applications, you'll probably find the ArcGIS API for JavaScript to be a nice fit.
Many beginning developers find the JavaScript, Flex, and Silverlight APIs easy to learn because of their supporting resources. In the ArcGIS Resource Center, you can watch videos, read tutorials, and examine working samples that are designed for beginners. Additionally, Esri has made sample ArcGIS server sites available so that you can practice with the APIs. In fact, you can get a JavaScript mapping application running on your machine with just a text editor and an Internet connection.
Building mobile applications
You can extend the reach of your services to a broad range of mobile devices, such as Windows smartphones, Apple iOS devices, Android devices, Tablet PCs, and in-vehicle mounted systems, by building mobile GIS applications. Often, you can start with a premade application or develop your own using an API. To learn more, visit the Mobile GIS page in the ArcGIS Resource Center.
Further reading
If you're interested in learning more about web GIS application design, deployment, content, and editing, see the Design concepts for web GIS applications book of this help section.