Steam has made some changes to the client software in an attempt to reduce the number of phisher/hacker accounts. Rest assured that the following doesn’t apply to you if you have ever spent at least US$5 lifetime at the Steam Store.
UPDATE 5/31/15: Valve explains their reasons for having limited users to PC Gamer.
A limited user is any Steam account that has not yet spent at least US$5.00 at the Steam Store; such a user is similar to a universal free-to-play account. Limited User accounts have had many of the functions of the Steam client removed–mostly to prevent phishers and hackers from creating throwaway Steam accounts. Among the features that are now disabled for Limited User accounts include:
- Sending friend invites
- Voting or posting on anything in Steam Workshop, Greenlight, or Reviews for a game/software
- Opening text chat windows with another user or groups
- Gaining Steam Profile Levels and Steam Trading Cards
- Participating in the Steam Market
The above restrictions are lifted if the user buys a game(s) of at least $5 value in the Steam Store for yourself or as a gift, buys at least $5 worth of Steam Wallet funds, or adds a prepurchased Steam card to the account.
Limited User accounts can still play free-to-play games on Steam, promotional trial games like Free Weekends, receive and play gift games from another person, trade games and/or in-game items, and activate promotional CD keys (like from hardware companies or a Humble Bundle). However, none of these actions will earn full user access; at least $5 of funds and/or content must be purchased from Steam (or a Steam card from a third-party, and then applied) to remove the Limited User restrictions. Again, receiving a game(s) or in-game items as gifts will not remove the restrictions.