BITS (short for "British Isles Traveller Support") is a UK based organisation dedicated to providing a forum for Marc Miller's Traveller Roleplaying Game. It was founded in 1995 by Andy Lilly (who still co-ordinates the organisation). Within this remit, BITS supports all versions of Traveller (Classic, MegaTraveller, The New Era, GURPS Traveller, Marc Miller's Traveller, Traveller T20 and Mongoose Traveller) by:
• organising tournaments and demonstrations in the UK (and beyond).
• publishing quality adventures, supplements and rules for Traveller.
• aiding and encouraging members' submissions to magazines.
• collecting and publishing software role-play aids.
• bringing together players through a contact list.
Although BITS was founded in the UK, it has had members throughout the world as well as the UK. BITS was originally licensed to publish material for Traveller by FarFuture Enterprises, but now uses the TAS licence.
BITS was incorporated as a company ("BITS UK Limited") when GURPS Traveller was released to put the legal niceties in place to allow sales to the USA and beyond. However, as an organisation it is still run for the love of the game, and not for the money (fortunately!).
There has sometimes been some confusion about CORE and its relationship with BITS. You can find an explanation here.
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UK Legal Declaration of Registered Office:

BITS UK Limited is a company registered in England and Wales
with company number 3690795, VAT Registration Number 677 0752 08.