This question already has an answer here:

Has anyone used PostgreSQL with PostGIS successfully?

I am a semi-experienced ArcGIS user and want to build out a database and connect it to ArcCatalog.

I've scoured the internet for resources but nobody has really given a good walkthrough.

merged by PolyGeo Sep 22 '16 at 6:55

This question was merged with Connecting to PostGIS database from ArcMap for display and query without ArcSDE? because it is an exact duplicate of that question.