Calling cards are similar to business cards, but in the 1800's and after, a calling card was meant for people who went "calling". What's the difference between a calling card and a business card you ask? Business cards are cards for tradespeople-- now and way back in the 1800s. Calling cards are a bit different. Let me explain...
According to "Hints on Etiquette" published in 1834, if you are among the more fashionable people, "you must not pay a visit to a lady before two o'clock pm nor after four, as if you call before that time, you will interrupt those avocations which more or less occupy every lady in the early part of the day; if later than four o'clock, you will prevent her from driving out." How's that for specifics? No texting, no calling, no emailing.... just stop on by between the hours of two and four. If gentlemen arrived before four o'clock, it was good form to decline tea as it was too much trouble to make it before it was ready. Ladies were the only ones ever visited. Gentlemen visited each other at their clubs or at their place of business.
When a gentleman visits a house, he must leave his calling card in the foyer. If the gentleman is allowed into the house, he must never leave his hat in the hallway because it will make him look like he feels too much "at home". He must take it into the parlor. Before the 1830s' it was good form to turn down the corner of your calling card if you were visiting more than one person in the house. But by the mid 1800's it was good form to leave one card for each person. gentlemen only stayed for about 15 minutes at a time. It was far better for friends to regret your withdrawal than to long for you to leave.
Moreover, if a gentleman was invited to a ball by somebody he did not know very well, he would have left his card at the invitee's house so that when he is announced at the ball, they will be familiar with him.
Today, most people have business cards touting their professions. I still design and print calling cards for clients. It's so nice to have something physical, pretty and representative to them to hand to a new acquaintance. It's much more personal than a bump with a cell phone!
You can check out all of my calling card designs in my Etsy shop right here: https://www.etsy.com/shop/GildedSwanPaperie