I am still fairly new to Arduino and I'm curious if two separate Arduino boards can communicate with each other via Bluetooth (preferably without the aid of any external devices such as phones or tablets)? If so any information or links into how it can be done would be helpful!
Buetooth is essentially "serial by wireless". You could use the code in Serial Input Basics to receive the data and Serial.println() to send it. Note that at least one of the Bluetooth devices must be able to act as Master. The HC05 Bluetooth modules can act as master or slave but the HC06 can only act as slave.
For longer ranges you could use nRF24L01+ 2.4GHz transceiver modules - they are not expensive.
They have a serial cable replacement mode and a fairly straightforward pairing mechanism.
They're not the cheapest (more than £10 per module), if you're flexible about the protocol then the RF modules suggested above might be cheaper. I'm using only Bluetooth to simplify regulatory approval.