Inland marine covers loss to either your property or the property of others when it is in your care, custody and control, when the property in question is at a non-permanent location, in transport, temporary storage, or mobile. Property in question does not have to be business property (items owned), but may also be personal (guns, golf clubs, skis, etc.) This type of coverage can also be called a floater.
As for how the terms “inland marine” and “floater” came to be, indulge us in a little story:
Over 300 years ago, a collection of European merchants would meet at a coffee house to discuss their business transactions. Many were in the transatlantic cargo and shipping business, moving sugar cane & rum as well as other commodities around. Pirates were a fact of life, as was bad weather. The merchants, to collectively ease the individual pains when one ship or its cargo was lost, would each pay regular, smaller amounts into a fund, in order to “insure” against loss.
As these merchants expanded this concept, they took the original marine insurance idea and applied it to goods on barges in canals (floater) en-route to their final destination, and to ground-based transportation that worked for the marine merchant companies (inland marine).

The town these merchants were in? London
The name of the coffee house? Lloyd’s

Other events of significant note have created the modern insurance industry. Mrs. O’Leary’s cow (the 1871 Chicago fire) was responsible for an entire new insurance industry, starting with something called dwelling fire coverage, or the fire policy. The 1906 San Francisco earthquake (which actually affected an area from LA to Oregon) called for careful definitions of coverages and causes of loss.