(FORTUNE Small Business) – Greeting card sales have increased over the past decade and particularly since 9/11, which means that Valentine's Day--already America's second-largest holiday for greeting cards, trailing only Christmas--should be a real bonanza. And an estimated 100 million of this year's Cupidian missives will bear the imprint of the company that has become virtually synonymous with greeting cards: Hallmark.

Hallmark's origins begin with Joyce C. Hall--often known as J.C., partially in deference to his unusual first name--who was born in 1891. Hall wasn't a writer or an artist, but he had an instinctive feel for emotional expression that translated to his cards. He got his start selling imported postcards depicting sepia-toned dogs and generic glade scenery, first in his native Nebraska and then in Kansas City, Mo., where he arrived in 1910. He took a room at a YMCA and began wholesaling postcards by mail (generating so much response that the Y eventually complained about the volume of letters). His brother Rollie soon joined him, and they opened a shop called Hall Brothers.

Early on, J.C. conducted his own form of market research. "He'd watch people shopping," recalls his grandson Don Hall Jr., 48, who runs Hallmark today. "He'd take notes and ask people, 'I noticed you didn't buy anything there,' or 'Why did you buy that?'" As Hall correlated this information with sales patterns, he became convinced that people were craving a more expressive outlet than postcards could provide. He decided that greeting cards, with their inscriptions and larger format, held greater emotional appeal. The brothers began producing the cards in 1915 and thus were perfectly positioned when World War I cut off the supply of European postcards. As greeting cards entered mainstream culture--in part because they were the ideal medium for families writing to sorely missed GIs overseas--Hall Brothers grew, becoming a 120-man operation by 1922.

Around that time J.C. became intrigued by a story about the Goldsmiths Hall in 14th-century London. Each gold goblet, urn, or tray that the smiths there produced carried a special insignia indicating purity--a "Hall mark." The term fascinated Joyce: "It not only said quality in an authoritative way but also incorporated our family name," he wrote in his 1979 autobiography, When You Care Enough. "Hallmark" first began appearing on Hall Brothers cards in 1928 and became the company's official name in 1954.

J.C.'s strong interest in branding emerged in other ways as well. A 1928 ad in Ladies' Home Journal made Hall Brothers the first card manufacturer to advertise nationally, and J.C. further raised the company's profile with a special display fixture in 1936. (Stores had previously kept greeting cards hidden away in drawers.) He also pursued media partnerships, most notably through Hallmark Hall of Fame, which has been a television mainstay since 1951. And the company's slogan, "When you care enough to send the very best," which debuted in 1944, now ranks among marketing's most iconic catch phrases.

As Hallmark became an American institution, the company's roster of contributors included such celebrated illustrators as Walt Disney, Grandma Moses, Norman Rockwell, and Saul Steinberg. By the time of J.C.'s death in 1982, annual revenues had reached $1.3 billion, a figure that has now swelled to $4.2 billion. The company is still based in Kansas City and still owned by the Halls, who've resisted entreaties to take Hallmark public. Donald Hall, 75 (J.C.'s son and Don Hall Jr.'s father), retired as CEO in 1986 but remains chairman.

As for the familiar cavil that Hallmark epitomizes middlebrow sappiness, well, that's a matter of taste. Coincidentally, one of J.C. Hall's favorite sayings was "Good taste is good business." One can hardly argue with his results.