Barter is a system of exchange by which goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money. It is distinguishable from gift economies in that the reciprocal exchange is immediate and not delayed in time. It is usually bilateral, but may be multilateral (i.e., mediated through barter organizations) and usually exists parallel to monetary systems in most developed countries, though to a very limited extent. Barter usually replaces money as the method of exchange in times of monetary crisis, such as when the currency may be either unstable (e.g., hyperinflation or deflationary spiral) or simply unavailable for conducting commerce.
While it may be free, there is no one monitoring the barter ads, so you must be aware of potential Craigslist scams, and realize that you are always at risk when it comes to meetups and exchanges. For example, about a year ago, I arranged to trade massage gift certificates for housecleaning. Since the individual was coming to my home, I was more nervous than usual. However, she offered good previous references, and we arranged for a time to meet when my husband would be home, in case an odd, unexpected, or even dangerous situation arose.
Although, as a general case, a ship unlucky in falling in with whales continues to cruise after them until she has barely sufficient provisions remaining to take her home, turning round then quietly and making the best of her way to her friends, yet there are instances when even this natural obstacle to the further prosecution of the voyage is overcome by headstrong captains, who, bartering the fruits of their hard-earned toils for a new supply of provisions in some of the ports of Chili or Peru, begin the voyage afresh with unabated zeal and perseverance.