Elasticsearch 5.0 introduces a significant change by removing the string type, which caused confusion due to its dual functionality for both keyword and full-text searches. To address this, the string type has been split into two distinct types: text for full-text searches and keyword for keyword searches, simplifying the process and eliminating the complexities associated with the previous model. Additionally, by default, string fields will now be mapped as both text and keyword, allowing for more efficient searching and aggregations without requiring reindexing. This update aims to enhance user experience by reducing complications and improving default mappings, while backward compatibility is maintained for existing indices, and automatic conversion is available for new indices to ease the transition. However, users are encouraged to update their templates and mappings in preparation for the eventual removal of backward compatibility in Elasticsearch 6.0.