What command is used to view new content as it is written to a log file?

The `cat` command concatenates and displays the entire content of a file to standard output at once; it does not continuously monitor for new content.

The `grep -f` command reads patterns from a file and searches for them in other files; it is used for pattern matching, not for continuously displaying new log file content.

The `cut` command is used to extract sections from each line of files, typically by bytes, characters, or fields; it is not designed for continuous monitoring of new file content.

The `tail -f` command displays the last portion of a file and then 'follows' it, continuously outputting new data as it is appended to the file. This is crucial for real-time monitoring of log files to observe events as they occur.