[agile] Difference between agile and iterative and incremental development

What are the difference between Agile and iterative and incremental development? Is Agile considered as iterative and incremental? Some info shown the Agile is the latest of iterative and incremental. I need a clear clarification on this.

Iterative development implies revisiting usual waterfall model steps over the course of product lifetime. The stages can even overlap, i.e. while doing end-to-end testing you could already start preparing new requirements.

Incremental development means you roadmap your features and implement them incrementally.

Agile aims at creating "potentially shippable product" after every sprint. How you achieve it is a different story. Agile tries to employ "best" techniques from various fields (e.g. extreme programming). Agile does not exclude running neither incremental nor iterative development.

Some important and successfully executed software projects like Google Chrome and Mozilla Firefox are fine examples of both iterative and incremental software development.

I will quote fine ars technica article which describes this approach: http://arstechnica.com/information-technology/2010/07/chrome-team-sets-six-week-cadence-for-new-major-versions/

According to Chrome program manager Anthony Laforge, the increased pace is designed to address three main goals. One is to get new features out to users faster. The second is make the release schedule predictable and therefore easier to plan which features will be included and which features will be targeted for later releases. Third, and most counterintuitive, is to cut the level of stress for Chrome developers. Laforge explains that the shorter, predictable time periods between releases are more like "trains leaving Grand Central Station." New features that are ready don't have to wait for others that are taking longer to complete—they can just hop on the current release "train." This can in turn take the pressure off developers to rush to get other features done, since another release train will be coming in six weeks. And they can rest easy knowing their work isn't holding the train from leaving the station.<<

Incremental development means that different parts of a software project are continuously integrated into the whole, instead of a monolithic approach where all the different parts are assembled in one or a few milestones of the project.

Iterative means that once a first version of a component is complete it is tested, reviewed and the results are almost immediately transformed into a new version (iteration) of this component.

So as a first result: iterative development doesn't need to be incremental and vice versa, but these methods are a good fit.

Agile development aims to reduce massive planing overhead in software projects to allow fast reactions to change e.g. in customer wishes. Incremental and iterative development are almost always part of an agile development strategy. There are several approaches to Agile development (e.g. scrum).

Agile is mostly used technique in project development.In agile technology peoples are switches from one technology to other ..Main purpose is to remove dependancy. Like Peoples shifted from production to development,and development to testing. Thats why dependancy will remove on a single team or person..