When you visit any of our services, our servers log your IP address, which is a number that is automatically assigned to the network your computer is part of. 3.7 Content Recommendations
We may process information collected under this section 3 so that content, products and services shown on the pages of the Steam store and in update messages displayed when launching the Steam Client can be tailored to meet your needs and populated with relevant recommendations and offers. This is done to improve your customer experience. You can prevent the processing of your data in this way by turning off the automatic loading of the Steam store page and of Steam notifications in the "Interface" section of the Steam Client settings. Subject to your separate consent or where explicitly permitted under applicable laws on email marketing, Valve may send you marketing messages about products and services offered by Valve to your email address.
Is my data used in profiling? 
can be tailored to meet your needs and populated with relevant recommendations and offers