The first writing materials were developed in 4000 BC but how did you get your letter to its destination?
The fastest way of travel was on horseback - so the only way of communicating over distance was by messenger.
One of the most famous messengers in history was the Greek soldier who hurried to Athens, bringing the news of the Greek victory over the Persians at Marathon in 490 BC.
The Marathon messenger died of exhaustion after covering a distance of about 26 miles - the same as the modern Olympic sporting event named in his honour.
The soldier was just one of thousands of foot messengers who formed the most reliable way of sending messages in the ancient world.
'I galloped, he galloped - we galloped all three.'
Browning's poem with the three messengers is very romantic - but misleading. Mounted messengers didn't gallop - or at least not if they wanted their horses to end the day alive.
However, 'He walked, I trotted, we ambled all three,' wouldn't have sounded quite so dramatic.
In fact, for any journey of more than five days, a man on foot is faster than a horse, since the horse requires more rest and feeding.
The only time mounted messengers really can gallop is when there are fresh horses waiting for them every few miles. This was the idea behind the U.S. Pony Express which, for a few months in the early 1860s, became the ultimate form of mounted messenger service.
The Pony Express covered a gap in the growing but still incomplete U.S. telegraph system from St Joseph in Missouri to Sacramento in California. That was almost 2,000 miles (3,200 km) and using relays of messengers and horses, the Pony Express covered this distance in just 10 days in summer and 16 in winter. The messengers rode stints of 100 miles each, changing horses every ten miles.
The Pony Express lasted only 18 months or so, and shut down very quickly once the transcontinental telegraph had been completed in October 1861.
William Russell was the co-founder and public face of the ill-fated Pony Express.
He was a natural salesman and hustler, who had learned about trading on the old American frontier as a teenager. He opened up a shop, which earned him enough to buy his own house, but he jumped on a chance to set up a wagon freighting business between Missouri and New Mexico.
Russell's adventurous and reckless streak persuaded his partners to set up the Pony Express message courier service in 1860. It traded for around a year and a half, but never managed to make any money and collapsed.
Russell never recovered from financial ruin; he lost his 20-room mansion, stable and coach house, was snubbed by financial backers and moved in with his daughter and later with his son. Although he has now faded into obscurity, the Pony Express became a household name as a breeding-ground for heroes in Hollywood westerns.
In Britain, between the 17th and early 19th centuries, the quickest way of sending messages was by stage coach.
'Quick' was a relative term. The journey from Bath to London - around 100 miles - took the best part of three days in the late 1600s.
Things started to speed up after 1784, when the Post Office introduced fast mail coaches. These were lightweight, well sprung and well guarded, with new teams of horses waiting every 20 miles or so along the route.
The big change came after 1800 when John MacAdam pioneered surfaced roads (he used tar and for a while this was known as tarmacadam - later shortened to tarmac). Together, the new coaches and roads reduced journey times dramatically - from London to Bristol in under 17 hours, London to Liverpool in just over 21 hours and the journey to Glasgow in just under two days. Britain was the first country in the world to introduce mail coaches, but the rest of Europe and America soon followed suit.
The thing about pigeons is that they have an uncanny instinct that always takes them back to their home loft. We still don't know for sure how they do this - the latest theory is that iron in the inner ear serves as a sort of natural compass.
By basing the pigeon's home loft in a particular spot, then sending birds out in baskets to where the messages start their journey, you can use them as flying postmen. The ancient Egyptians were probably the first to do so, around 3000 BC.
Between about 770 BC and 390 AD, the Greeks used pigeons to carry the results of the Olympic Games.
Pigeons were used extensively during the First World War. About 20,000 of them were killed - and some 30 British carrier pigeons were awarded medals for bravery.
