Definition - What does Deprecation mean?
Deprecation is the process of marking attributes or features that should be avoided by users, including Web developers. Deprecation may be applied for various reasons, including one of the most common, which is the availability of more practical and effective alternatives.
Techopedia explains Deprecation
Applications or software programs may have deprecated features, due to security risks or damage to software and devices. Deprecation also occurs when a feature is upgraded, or an alternative option is provided. However, to avoid technical issues, such as backward compatibility, the deprecated attribute is not removed from the software until the developer can correct the problem or produce a more stable and useful code.
A good example is when a developer releases a new application programming interface (API), which then creates deprecated values. To avoid serious technical issues, the deprecated parts should never be used.