Steam Guard has changed much recently, with the prior change being email codes when logging into new devices and email confirmations for trades. Now Steam is pushing for Mobile Authentication. This is similar to the emails, except it is all done within the Steam Mobile App for iOS and Android devices. When you click the Steam Guard Tab in the mobile app, you will see a code with a bar that reduces in size and then changes to red as time passes. You have 30 seconds to put this code in when you login with your account credentials. After 30 seconds, a new code is generated.
To enable Steam Mobile Authentication, simply login to the Steam Mobile App, select Steam Guard, select Steam Guard Settings, then choose Steam Mobile Authenticator. If you need additional help with setting up Steam Guard Mobile Authentication, visit the official Setup Guide.

Note: The Steam Mobile Application is only available on iOS, Android[play.google.com], and Windows Phone[www.microsoft.com].

Escrow by definition is a bond, deed, or other document kept in the custody of a third party, taking effect only when a specified condition has been fulfilled. Steam has begun to call their new Escrow feature "Trade Holds".
So what are these trade holds exactly? Essentially, Steam is forcing Mobile Authentication on everyone. For those that cannot use or choose not to use Mobile Authentication, your trades will be subject to trade holds. This means that once you enact a trade with another player, the items in the trade will be held by Valve for up to 3 days 15 days. This gives both users time to cancel the trade. After the cooldown period, the items will delivered to their recepients. For more information on this visit Steam's official Documentation or view the screenshot below.

Here you will see how trading will look like with the use of Steam Mobile Confirmation.

Before you do any trading, the Confirmations page of the Steam Mobile App will look like this.


First you will Trade someone or use a trade offer.

Upon accepting the Trade or Making the Trade Offer, you will be prompted with a dialogue telling you to confirm the trade with the Steam Mobile App.

After opening the app on your mobile device and navigating to the Confirmations page, you should see a pending trade to confirm.

After clicking this pending trade, you will see the contents of the trade, and you will have the options to "Cancel" or "Send Offer" (confirming the trade).

After you confirm the trade and you have no other trades to confirm, your Confirmations page will look like this.

Similar to trade holds, Steam is now implementing market holds. A user must have had mobile authentication enabled for the past 7 days to avoid trade and market holds. Market holds will be held by Steam before they are listed on the market. These holds can last up to 15 days. Once the hold period is over, the item will be listed on the market. If you cancel a listing that is currently on market hold, you will NOT be subject to a trade or market ban. Steam Community Market holds will start on March 9, 2016.

Read the Steam blog post about account security for a detailed explanation on why Steam implemented holds: http://steamproxy.net/steamstore/news/20631/

The simple answer is:

• Download the Steam Mobile App on your Android, iOS or Windows Phone device
  
• Enable mobile authentication
  
• After 7 days you will no longer be subject to trade holds
  
• Avoid trading with users that do not have mobile authentication or you will be subject to a trade hold with them.

• Some users in the comment section of this guide have recommended trying Android emulators.
  
• The most common recommended emulator is BlueStacks 2, which is free.

As of March 9, 2016 several changes will be coming:

• The first change is that trade holds with new Steam friends will now last 15 days instead of the original 3 days.
  
• Trade holds with long-time Steam friends will last 1 day.
  
• Listing on the Steam Community Market will have a hold of 15 days before an item can be sold. See the section on SCM for more information.
  
• Steam Support will no longer restore items that have left accounts following a successful trade or market transaction (a process that previously created duplicates of original items)

• Steam is offering a 5-35% discount in the community market until December 16, 2015 at 10am PST for enabling Steam Guard Mobile Authenticator
  
• Starting December 9th, 2015 Trade Holds (escrow) will begin for users that DON'T enable Mobile Authentication. Trade holds can last up to 3 days (72 hours).
  Trade holds with new Steam friends will now last 15 days instead of the original 3 days. Trade holds with long-time Steam friends will last 1 day.
• Only one Steam Account can be linked to a mobile number
  
  Steam has changed this Hooray!
• Starting March 9th, 2016 Market Holds (escrow) will begin for users that DON'T enable Mobile Authentication. Market holds can last up to 15 days (360 hours).
  
• Starting March 9th, 2016 Steam Support will no longer restore any items that have left your account. This means an end to dupes, unless some bug allows for the creation of more in the future.

This affects all traders in that:

• a) You are forced to use the Steam App mobile authentication if you want to avoid Trade Holds
  
• b) If you trade with someone who isn't using mobile authentication, you will then have your items on Trade Hold
  
• c) If you do not have an iOS, Android, or Windows Phone device you cannot download the Steam Mobile App and will be subject to Trade Holds
  
• d) If you are using mobile authentication but your device runs out of power, you cannot confirm trades until you charge it
  
• e) Anyone with alt accounts for item storage or trading bots will have to figure out a new ways to deal with this
  You can now use your number on multiple accounts.
• f) If you are using mobile authentication but your device runs out of power, you cannot log into Steam
  You can now generate "backup codes" that can be used at any time. These are different from the recovery code!

For more information visit: https://support.steampowered.com/kb_article.php?ref=8625-WRAH-9030
Read the Steam blog post about account security for a detailed explanation on why Steam implemented holds: http://steamproxy.net/steamstore/news/20631/

Side note: Feel free to join my trading community: http://steamproxy.net/groups/SuddenTrading

1) What can I do if I do not have a phone or device that can download the Steam Mobile App?

• Try an Android emulator such as Bluestacks 2 if you want to avoid trade and market holds
  
• Try Jessecar's Steam Desktop Authenticator
  https://github.com/Jessecar96/SteamDesktopAuthenticator
  
• Get a free phone number from Google Voice or any of the various texting apps

2) Can I still trade and use the market without mobile authentication?

• Yes, you can still trade and use the market, however you will be subject to trade and market holds. Market holds apply to listing an item, not purchasing.

3) I have enabled Mobile Authentication, why do I still have trade/market holds?

• After you enable mobile authentication, you have to wait for 168 hours (7 days) to pass. After that you will no longer have holds.

4) How can I check if I have waited the full 168 hours (7 days)?

• For some users, going to the community market in Steam will show either the date they enabled mobile authentication or the time remaining on the 7 day cooldown. If it shows neither, you're out of luck and just have to wait until it starts working.
  
• You can double check if it is up by sending a trade offer to a stranger. If it says that there will be a 15 day hold on the trade when you send it, then you have either not waited the full 168 hours or you did not setup mobile authentication in the Steam app.
  Here is my trade offer link so you can test it: https://steamproxy.net/tradeoffer/new/?partner=50717057&token=4HZ45kY1

5) Your guide only shows TF2 items in the images. Does this mean it doesn't affect my CS:GO, Dota, and other tradable items?

• No. This guide applies to all tradable items for any game or non-game (Steam trading cards, tradable games, ect.)

6) Can I still gamble my CS:GO skins on InsertWebsiteHere.com without mobile authentication?

• I do not know the rules of your third-party gambling site. I would imagine that most gambiling sites do not allow users with trade holds to participate. Having mobile authentication would ensure that you could participate.
  
• Also Valve recently released a statement in which they said they do not condone skin gambling and are making attempts to shut down skin gambling websites. If you participate in such activities, you do so at your own risk!
  http://steamproxy.net/steamstore/news/22883/

7) I get this message "Your escrow is not enabled or 7 day limit is not over." when trying to use my items/skins on a website. What does it mean?

• Reread this guide
  
• View this Guide: http://steamproxy.net/sharedfiles/filedetails/?id=830681600
  
• Also refer to question #3 of the FAQ.

8) Will Valve change all of this?

• Valve has made several changes since Mobile Authentication first came out. They are likely to make more in the future, but I do not forsee them doing away with 2-Factor authentication and trade/market holds.

9) Are you affiliated with Valve or Steam?

• No.

10) Why did you delete my comment?
Comments may be deleted for the following reasons:

• It was spam.
  
• It was misinformative or unproductive.
  
• It wasn't in English.
  
• Because I can.

11) Can I add you to ask a question about all of this?

• I will only respond to friend requests from people that are in my trading group http://steamproxy.net/groups/SuddenTrading
  
• You MUST speak English. I'm not going to waste time trying to translate or decipher your broken English.
  
• Only add me if you still have questions after reading this guide IN ITS ENTIRETY, as well as the information on the Steam Support pages that I have linked in the guide.

　　　　　　　　　　　　　　　　　　
　　　　　Did this guide help you? Like it and share with your friends!

Also feel free to join my Steam Trading Group: http://steamproxy.net/groups/SuddenTrading
　　　　　　　　　　　　　　　　　　　and/or
Feel free to join my Steam Gaming Group: http://steamproxy.net/groups/suddenentropygaming