When you type in a URL (such as www.fubar.com), you are making a request for information. Once the request is recieved, information is transmitted to the requesting machine from the host. Upon completion, a small packet is sent to the requesting machine that asks that machine for a confirmation that all data was delivered succesfully. An acknowledgement is then sent, and the process repeats every single time you request a peice of information. Even if the information is not present, there is at least data introduced denoting that fact. That's it. Dirt fuckin simple.
Now, computers can move data two ways, in and out at the same time. (At least most protocols allow that). The same is not true of individuals, people, humans. When a person transmits (speaks), the data line must move one way, until all relevant information is delivered. It is at this time that an acknowledgement, or reciprocating data can be introduced from the reciever (listener). This can continue back and forth for as long as it takes to process all the data that has been flying around. This metaphorical data exchange is usually referred to as a "conversation" when conducted between living persons.
Perhaps someone should tell Tanya that.