Magento 2.1.18 is the final 2.1.x release. After June 2019, Magento 2.1.x will no longer receive security patches, quality fixes, or documentation updates.
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Component development

Magento 2 is flexible and as a result has varied functionality, so developing a component in Magento takes into account a number of different of the following topics. Please read the information on compatibility — Service Contracts, Design Patterns, and the information on Dependency Injection, Routing, and Working With Public Interfaces and APIs closely; they are essential to creating a good Magento 2 component.

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