Lookup Table Variable

Using the Advance Lookup Table variable for server Google Tag Manager, you can return values depending on the specified conditions. The main advantage is that you can set conditions using different parameters like equals, start with, contain, RegEx, etc. 

You can use either constant or variable. Advanced lookup table variable (internally, we also call it If/Else variable) can be helpful, for example, when setting up server-side tracking for multidomain, when you need to fire pixel or transport URL depending on the hostname. Or maybe you want to send custom parameters for your FB events depending on the product name.

Another widespread use case is creating ecomm_pagetype type for Google ads remarking tags. You can set page type depending on page URL, event type, etc.