what is the use of Host in Technical system

Hi experts,

While creating Technical sytem what is the use of creating Host.

while creating Business System we create Logical System.When we are creating for Sap system then there we give client logical sytem name,but while creating for third party systems what is the use of it.....

while creating Technical system and Business system v have 4 radio buttons

Web As ABAP

Web as Java

Standalone

thirdParty

what is the use of Standalone when and in which senario we use this Standalone.

Note:valuable anser will be rewarded.

Regards,

Phani