The combination of printing technology, cheap postage and efficiency of the postal system led to a massive increase in the sending of picture postcards. They were a quick and low-cost means of communication before the telephone was widely used. “Postcards were the prime social networking tool of its days,” according to Dr Julia Gillen of Lancaster who heads the Edwardian Postcard Project, fascinating research into the era and how the new medium affected communication. 

With up to six post deliveries a day in major cities – sometimes as many as 10 in London, people knew they would be received within hours. As such around six billion cards were posted in the period: you could even send postcards from trains. Pictured here is a photographic postcard depicting the Proclamation of King George V in 1910, one of the many in the collection of David Shaw Postal History dealers.

Brian Lund, publisher of Picture Postcard Annual, agrees that the “golden age” of picture postcards was from 1902–1918. “That was when most were produced, collected and sent. The absolute peak year was 1907. From 1902–1918 you see most areas of human life covered on postcards but after that it was mainly comic cards and touristy views.” Some Edwardians even commissioned their own photography, says Dr Gillen whose Twitter feed is a treasure trove of missives from the fashion-conscious era.

Many poignant correspondences were sent between soldiers and their lovers during WWI. Embroidered silk postcards were a particularly popular memento to send from the frontline. Brian believes postcards provide unique insights into social history. “Postcards are endlessly fascinating and multi-faceted: picture, artist, photographer, stamp, postmark, message. All of human life is there. If you’re interested in anything, you’ll find it documented on postcards."

Cartoon-style saucy postcards became widespread in seaside resorts from the early 1930s onwards. "After 1918 the popularity of sentimental postcards sharply declined, making way for the comic postcards that would eventually define Bamforth & Co," writes Marcus Hearn in his book Saucy Postcards: The Bamforth Collection (published by Constable & Robinson). It charts the background of James Bamforth and his West Yorkshire studio's innuendo-laden postcards, which are highly collectible today.

Donald McGill was perhaps the most controversial postcard artist – some of his smuttier designs were banned for indecency by the newly elected Conservative government in the early 1950s. During his 60-year career, he produced over 12,000 postcard designs which became synonymous with tongue-in-cheek seaside souvenirs. You can see the offending postcards at the late artist’s eponymous museum on the Isle of Wight.

The sixties and seventies brought in the era of glorious technicolour to the postcard stands. John Hinde Studio was highly influential in the art of postcard photography with its vivid colours and depiction of everyday life in Britain’s holiday resorts. The photographer’s nostalgic and kitsch postcards are now highly collectible, especially those in the series commissioned by British holiday camps Butlin's.

Long time fan of British seaside nostalgia Glen Fairweather has built up an impressive database of old postcards, which he showcases on his Flickr pages. “I used to collect mostly old British postcards for nostalgic reasons – it reminded me of family holidays and growing up in England during the 1970s and 1980s when the whole holiday scene was so different to what it is now,” he says.

Glen puts his postcard habit down to a fascination for social history – he's charmed by the images and messages sent from a lost era. “I’ve always had an interest in it [social history], especially after the war years and how the British [people] went about their lives. Postcards give a glimpse into this,” he says. Glen, who now lives in the USA, also founded the Butlin's Memories website in 2000.

Rare antique postcards can command impressive prices – one written from the Titanic sold for £14,000 back in 2002. According to eBay, in the last three months 180,000 postcards have been sold on its site, which equates to one every minute. There are currently more than 3,000,000 collectible postcard listings live, with designs ranging from seaside humour to round-the-world.

Someone shining the spotlight on the lost art of postcard writing is Tom Jackson. He recently released a book (pictured) off the back of his hugely popular Twitter account @PastPostcard. In its introduction, author Mark Haddon says: "This book is not quite visual art and it's not quite social history. It's a collection of very short and somewhat cryptic stories set in the drowned Atlantis of the sixties and seventies."

Tom says he became fond of postcards as a child – both keeping those he received and spending his holiday pocket money on cards as souvenirs. “I stuffed them in a shoebox, then about 20 years ago I got a bit more interested in postcards and started collecting them in a more serious way – particularly cards from the 1900s. But any that interested me really,” he says.

In today's seaside resorts and tourist destinations, you’re far more likely to see someone wielding a selfie stick on holiday than putting a pen to postcard. But despite the decline of this classic travel memento, there may be hope yet. Postcard app TouchNote has brought the tradition into the 21st century using mobile phone technology and personalisation – over 9 million postcards have been sent through the service to date.

But if even that still seems a little too traditional for you, today you can send a coconut instead? The cumbersome but cute hand-painted "cards" are popular among tourists in Hawaii, although Naomi Young of Coconut Messages modern regulations mean they have to be inspected by the USDA, which is putting many off. 

She picks her coconuts from her own farm on Kaua'i before hand painting them with personal messages and pictures. "Sending a coconut is far more impressive than any other cards," she says. "It makes people smile, especially kids, and it will last more than 50 years. When I ship coconuts, I feel like I am sending their dream with great memories." And who can argue with that?