Trade is buying stuff from a place of origin in order to sell to the place of destination. optimally-like this is done in a manner or fasion to generate profit for the "trader" - the person who does the trading.
Station Trading Edit
Another type of trading, known as "station trading," involves creating buy and sell orders within the same station, flipping items for a profit. Station trading scales very well with capital, as it gives percentage based returns.
For more information on station trading, see: http://eveonlineiskguide.com/eve-online-isk-station-trading-i/