One
of Mark Twain's typewriters, a Hammond model circa 1880

Who was
the first writer to submit a typewritten manuscript?
Mark Twain with "Life
on the Mississippi" (1883). A sucker for new gadgets, he was one of
the first people to buy a typewriter, calling it a "curiosity-breeding
little joker."

What
people first kept written records?
That honor probably goes to the ancient
Babylonians. Clay books have been found containing land sales, business agreements,
and judgments—dated at more than 5,000 years ago.

Who
invented the modern book?
Most
people credit the Chinese with inventing books as we know them today. Five
hundred years before Johannes Gutenberg became famous for printing with movable
type, the Chinese had begun doing so using porcelain or metal plates. In
addition, the Chinese were creating covers and tide pages and were binding
manuscripts in a similar way to our modem book.
https://www.inspirationline.com/Brainteaser/books.htm

In
1972, Ray Tomlinson sent the first electronic message, now known as e-mail, using
the @ symbol to indicate the location or institution of the e-mail recipient.
Tomlinson, using a Model 33 Teletype device, understood that he needed to use
a symbol that would not appear in anyone's name so that there was no confusion.
The logical choice for Tomlinson was the "at sign," both because it
was unlikely to appear in anyone's name and also because it represented the word
"at," as in a particular user is sitting @ this specific computer.
However,
before the symbol became a standard key on typewriter keyboards in the 1880s and
a standard on QWERTY keyboards in the 1940s, the @ sign had a long if somewhat
sketchy history of use throughout the world. Linguists are divided as to when
the symbol first appeared. Some argue that the symbol dates back to the 6th or
7th centuries when Latin scribes adapted the symbol from the Latin word ad, meaning
at, to or toward. The scribes, in an attempt to simplify the amount of pen strokes
they were using, created the ligature (combination of two or more letters) by
exaggerating the upstroke of the letter "d" and curving it to the left
over the "a."
Linguists
are divided. Some think it originated in the early Middle Ages, when monks laboring
over manuscripts contracted the versatile Latin word "ad" - which can
mean "at" or "towards" or "by" - into a single character.
Most linguists, however, say that the @ sign is a more recent invention, appearing
sometime during the 18th century as a commercial symbol indicating price per unit,
as in "5 apples @ 10 pence." Yet another linguist, researcher Denis
Muzerelle, says the sign is the result of a different twist, when the accent over
the word "&#224" used by French and German merchants was hastily
extended.
But
last July an Italian researcher discovered some 14th-century Venetian commercial
documents clearly marked by the @ sign, where it was used to represent a gauge
of quantity, the "anfora," or jar. Giorgio Stabile also found a Latin-Spanish
dictionary dating from 1492 where "anfora" is translated into "arroba,"
a measure of weight. It's therefore natural that, in 1885 the "commercial
a" was included on the keyboard of the first model of Underwood typewriter
and from there migrated into the standard set of computing characters (such as
ASCII) 80 years later.

Evidence
of the usage of @ to signify French "à" (meaning "at") from a 1674 protocol from a Swedish lower court and magistrate (Arboga rådhusrätt
och magistrat)

https://www.inspirationline.com/Brainteaser/atsign.htm