Barter: intransitive verb: to trade by exchanging one commodity for another : to trade goods or services in exchange for other goods or services

farmers bartering for supplies with their crops

bartered with the store’s owner

:to trade or exchange by or as if by bartering
The thing about bartering is that there cannot be any money, or monetary medium (e.g. credit card) used in the exchange. 
Bartering is going to become the mode of exchange in the future – people are going to start relying on each other more and more as time goes on, primarily due to inflation.
Goods
The main way to barter is to exchange one form of physical commodity for another that has inherent value in the world – materials that have such value:
gold
silver
bronze
copper
art work
antiques
Of course, there are other products that can be exchanged if they are needed, or desired by others:
clothes
furniture
household linen
livestock
books/literature
technological devices
food (raw, or cooked)
salt (for the preservation of perishable foods)
Services
There are many services that people may provide others, in exchange for some other service. For example, a hairdresser may agree to do someone’s hair once for some type of exchange, or regularly for some type of ongoing barter, such as cleaning, babysitting, cooking, gardening, etc. The services offered do not have to be by anyone who has formal training in the area unless it is required by one, or both parties. Goods may also be swapped for services.
I.O.U. (I Owe You: A Written Agreement)
Bartering is usually accomplished via verbal agreements, but in cases where the individuals doing the exchange are unfamiliar with one another, or if there will be a long time before the agreement is fulfilled, then we have an I.O.U.
For more information on bartering, how to draw up an agreement, etc., go here.