The Raspberry Pi has a built in UART. This can be use as a serial port console. To connect to laptop a 3.3v FTDI breakout board is used.
If a monitor and ethernet connection is not available and you need to see the boot up message a serial console is a possible solution. Using a 3.3v FTDI breakout board, wire up the connection as shown:
To use it as a console, minicom software would need to be install first.
sudo apt-get install minicom
Then start the software:
minicom -b 115200 -o -D /dev/ttyUSB0
On your laptop start the terminal software and set it to baud rate to 115200. You should then get the console output like this:
You can now logon as normal.