Private Tracker

A private tracker is a type of tracker that requires you to be a member to view/download content and restricts who is allowed to join. The only way to get onto this type of tracker is to get invited, get accepted through an interview process, or register during an open registration period.

These trackers have rules that users must follow such as how active members must be, how much they have to upload, how long they have to seed, and what content can be uploaded. These rules can put off a lot of newcomers and shouldn't be taken lightly, failing to follow the rules laid out by a tracker can result in your account having privileges revoked or being disabled. Members are typically only allowed one account per lifetime so tread lightly.

Members are rewarded for following these rules through access to some of the greatest online media libraries in existence. Despite the number of users being much lower than public trackers, content is typically greater due to the dedication of the users and the rules that are to help promote sharing amongst one another.

Advantages
There are some private trackers that are very easy to get into and have a large user base, and there are also very exclusive trackers that thrive on a small but dedicated user base, each has its own advantages and disadvantages.

Private trackers have much greater control over the content that gets uploaded. There are often rules enforcing who can upload, what can be uploaded, how files can be named, and how content is organized. These rules are generally for the betterment of the community and are used to keep consistency.

The rules that are in place on a tracker are in the best interest of the users, one of the biggest advantages to the rules is that the retention on files often ends up being much longer than on a public tracker, or almost anywhere else on the internet. Members are encouraged to seed content as long as they can and as a result content that is years old is often still well seeded whereas on public trackers it could have died long ago because no one feels the need to seed.

Users are encouraged and sometimes rewarded for uploading as much content as they can to other users on the tracker. This leads to a lot of members to renting seedboxes, dedicated servers located in or near data centers with much higher than average upload and download speeds. These are used on new content a lot, giving them extremely fast speeds before eventually being left to seed by mostly home connections for longer periods of time.

Often times a tracker fills a niche that attracts users with common interests and ideas, this is when a community really thrives. Private trackers can bring members together through the forums, competitions, comments, or IRC.

Private trackers inherently offer security benefits in a number of different aspects. Files uploaded are less likely to include viruses or not be labeled incorrectly, this is because if a user knowingly uploads bad content they risk having their account disabled on the tracker, or at the very least having their upload privileges revoked. Another security aspect is that you are statistically less likely to receives copyright notices without external protection (eg. VPN or seedbox). This does not mean you're safe if you aren't hiding you IP address, this only means there have been less actions taken against private tracker users since they do not offer as much of a return for copyright trolls due to smaller user bases than public trackers. Put simply, you're more safe because you're not worth their time in most cases.

Disadvantages
Respected private trackers can be a challenge to get into, they often require you to have shown on other trackers that you are capable of being an outstanding member. This is the biggest hurtle for a lot of newcomers as it seems like you need experience to gain experience. There are a few ways to get around this, you can sign up to a private tracker during an open registration period, you can get invited through an application that doesn't require prior experience, or you can be invited by a friend who will 'vouch' for you.

After being invited the rules can be hard for someone to adapt to if they're used to downloading off of public trackers. Users must make sure they upload enough content relative to what they download, seed for a minimum amount of time, and visit/participate on the tracker often (usually every 30-90 days.) If these rules aren't followed then restrictions or disabling are a good possibility.

History
Private trackers started appearing as early as 2004 when the BitTorrent protocol started to become more popular and BitTorrent Inc was officially formed. The need to put restrictions on members who could join the tracker came primarily because of malicious and poor quality uploads, things that plagued previous P2P services before it such as Napster and LimeWire.

There are only a handful of private trackers that still exist today that were created during the original uprising. Most of them have been shut down due to pressure from big studios or just owners moving on with their lives.

Trivia

 * WDMA sites are one of the most exclusive and secretive sites around, not much is known about them except that they spawned from Something Awfuls BitTorrent Barnyard, WDMA being an acronym for "Where 'Da Movies At"