The ZIP code has 2 parts. First is a 2 number digit which is the sorting facility which is in the center of every county. The choice to place the sorting facility in the center of the county is for ease of distribution. The second part will have the sorting number. This is a unique 4 character alpha-numeric code that would define the exact address of the location. This is a preprogrammed database. Because people are not computer databases, the actual address still has to be written down. The only difference is those with a Private Address service. This will be addressed in another page. The second part of the ZIP code might look like 7DFH. This character code is listed with every database and can grow as the need arises. Therefore, if a single family home is converted into a 2 unit apartment building, then the address’s ZIP code will convert the original ZIP code for the lowest floor unit, and new codes will be assigned to the next units. The address could technically be written without the ZIP code, but it might get lost in the mail system, and will definitely take longer to deliver as the sorting system will have to figure out the address. With that in mind, it is always best to provide the complete ZIP code.