Christie’s held their first-ever online-only sale in December, for the Elizabeth Taylor collection. This 10 x 10in (25.5 x 25.5cm) Portrait of Elizabeth Taylor by Hiro Yamagata (b.1948) made $108,000, a world auction record for the artist. The estimate was just $200-300.

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Online bidders made up 29% of total bidders in Christie's sales globally in 2011 (not including the online-only auction). Last year Christie's Live, their online bidding platform, attracted 25% more bids than in 2010.

In December last year Christie's held their first-ever online-only sale as part of the sales series dedicated to the Collection of Elizabeth Taylor, running parallel to the live auctions in New York.

It brought in more than $9.5m in total sales, with bidders from 25 countries worldwide.

US-based Christie's senior vice president, digital media manager Michael O'Neal toldATG: "It has been this huge acquisition tool. For people that are afraid of the brand or have reservations about participating in 'online' fashion, those barriers have been broken down."

He feels that the key to online sales is in getting beyond the 'mystique' of auctions.

"It's about saying 'listen, you may not have a PhD in our history, you might not have come from this family of blue bloods... those are the misperceptions of participating with Christie's, you don't need any of those things. If you come in we're open, you can come in like a museum and get pretty close to the art, you don't need an invitation.

"You can be anonymous, you don't need to be dressed in a certain way. So many people have these misperceptions, that all auctions are these black-tie evening sales, with multi-million dollar pictures. It is either that perception or eBay, and I think it is that middle ground people don't really understand.

"We've seen the take-up rate improve year after year as that message has come be a part of this."

While Christie's accepts absentee bids left through 'mobile platforms' - such as an iPhone app, iPad app and an android app for example - Mr O'Neal said this year they would be looking at the possibilities of real-time bids for 'the mobile population'.

Matthew Girling, CEO of Bonhams UK, Europe and the Middle East, said: "Over the past year there has been a dramatic increase in clients who have registered for online bidding and Bonhams is committed to the development of this online facility.

"Early indications show that our investment in online bidding is increasingly successful. It will doubtless play a key part in the future of the auction industry. An indicator of this is evident from one four-month period last year where we had 12,000 new bidders register to use the system."

The top lot successfully bid for online to date is $650,000.

A Sotheby's spokesman said: "Online sales is an important and growing part of Sotheby's business and we will be adding new features to accommodate the increasing demand.

"Other than the Declaration of Independence, which sold for $8.14m in 2000, to date the highest winning bid is just shy of $1m and the highest underbid exceeds $15m."

The US document - one of only 25 known copies from the first printing and one of the best-preserved - was sold in an online auction.

Figures released in January by US-based auction house site HA.com, run by Heritage Auctions of New York and Dallas, showed it was now ranked as one of the top 3000 of all sites in the US (to put that into perspective, there are over 150 million American websites), according to Compete.com, a website devoted to monitoring web traffic.

HA had nearly 725,000 unique visitors to its site in that month, which the company says is "nearly double the combined total number of unique visits to the websites of Heritage Auctions' five closest competitors".

Co-chairman James Halperin said: "Our exact number of unique visitors in January was actually 724,931. No other major auction house came close to those numbers. We put a tremendous amount of research and time into making our website comprehensive, customer-friendly and easily accessible. Collectors, historians and art aficionados alike have responded with great enthusiasm."