We rely on those cards to express the thoughts and feelings that so many of us have trouble articulating.
But have you ever wondered who's actually behind those poetic, funny, or cheerful expressions? Have you thought about who is coming up with the words we so often can't?
At Hallmark alone - the largest manufacturer of greeting cards in the US, which had $3.8 billion in consolidated revenues in 2014 - there are 24 employees who are responsible for writing cards.
One of them is Diana Manning, a senior writer who has worked at the company's Kansas City headquarters for over 30 years.
Earlier this year, Business Insider spoke with Manning, who wrote her first greeting card at age 9 for her grandparent's anniversary - about what it's really like to be a card writer for Hallmark. Here's what she told us.
Some responses have been edited for clarity.