Data Migration Tool is a command-line interface (CLI) used for transferring data from Magento 1 to Magento 2. The Tool verifies consistency between Magento 1 and 2 database structures (tables and fields), tracks the data transfer progress, creates logs, and runs data verification tests.
The Tool operates in three modes:
Settings: migrates configuration settings
Data: bulk migrates main data in the database
Each mode consists of several steps that perform tasks specific to the mode (for example: URL rewrite, EAV, settings, etc.). Each step initially checks for data and structure integrity between Magento 1 and Magento 2 databases and, after verification succeeds, performs the transfer. The Tool then checks the volume of transferred data.