which one have u heard of when u fisrt new about bitcoin 

Tor is free software for enabling anonymous communication. The name is an acronym derived from the original software project name The Onion Router,[7] however the correct spelling is "Tor", capitalizing only the first letter.[8] Tor directs Internet traffic through a free, worldwide, volunteer network consisting of more than seven thousand relays[9] to conceal a user's location and usage from anyone conducting network surveillance or traffic analysis. Using Tor makes it more difficult for Internet activity to be traced back to the user: this includes "visits to Web sites, online posts, instant messages, and other communication forms".[10] Tor's use is intended to protect the personal privacy of users, as well as their freedom and ability to conduct confidential communication by keeping their Internet activities from being monitored

or 

Tails or The Amnesic Incognito Live System is a security-focused Debian-based Linux distribution aimed at preserving privacy and anonymity.[3] All its outgoing connections are forced to go through Tor,[4] and non-anonymous connections are blocked. The system is designed to be booted as a live DVD or live USB, and will leave no digital footprint on the machine unless explicitly told to do so. The Tor Project has provided financial support for its development

or have u not heard off any in relation to bitcoins

most of you will of heard of tor 
and some of tails
but both do the same think really 

so if u don't now about the then just google tor or tails and u find out more