This command is used to determine who was the last person to modify each line of a file in a Git repository.
The -w flag tells the command to ignore changes in whitespace when considering what constitutes a 'modification'. This allows for easier tracking of significant changes without interference from minor formatting edits such as indents or leading/trailing spaces.
The command can also be used with a variety of other flags. For instance, the -M flag detects moved or copied lines within a file, and the -C flag detects lines that were moved or copied from other files.