I'm working on an iPhone, and we are currently doing some user testing. This app deals with sensitive personal information. Security is definitely important for us. Instead of using username / password based authentication, we decided to go with 4 digits PIN/Passcode based authentication.

User needs to input the passcode each time he invokes the app, and we don't want to hurt the usability by forcing the user to use his password each time.

Currently, we call this passcode as PIN, because our web application uses the same terminology. User feedback suggests, our beta testers are unable to discover this feature.

When users login for the first time, we suggest them to set a PIN, so this is not something they can miss. I believe this is because iPhone users are more accustomed to the terminology "Passcode" then "PIN".

Maintaining consistent jargon seems like a no-brainer, but should we maintain uniformity between our products or with the system?

If you think about it, "PIN" is a concept people should be familiar with (ATMs use the term "PIN").

  • Is it possible that the issue isn't the term PIN but other usability issues around this?
    – user31143
    Mar 27, 2014 at 7:12
  • @dan1111 Unlikely, because when the user first logs-in, we show him a screen urging him to use the passcode feature.
    – Thilak Rao
    Mar 27, 2014 at 9:07
  • Can you show the first log-in screen and perhaps give more detail of what the testers are having trouble with? PIN seems pretty straightforward to me, so it is hard to see what the problem is.
    – user31143
    Mar 27, 2014 at 9:08
  • PIN should be numbers only. Baring that in mind, the answer becomes pretty simple, I think. Mar 27, 2014 at 18:25
  • Pin is indeed, numbers only!
    – Thilak Rao
    Mar 28, 2014 at 7:15

4 Answers 4


When users login for the first time, we suggest them to set a PIN, so this is not something they can miss.

This is where I disagree with you. When users download a new app, they don’t want to fill in every field appropriately. They want to reach the app, test it and see if it’s worth the time to register. Because of that, your workflow needs improvement. Let the user test the app as quickly as possible. You just need to ask for username/password or third party identity provider (Facebook, twitter, google, live-ID, …) and skip the rest.

Later, when the user are really working your app, remind them of setting the PIN/Passcode, and you’ll have the users’ full attention. If it’s still installed, they’re likely to keep it – if not, well, then it’s gone. You can do this with other fields as well, but only ask for info you really need.

On iOS you should call it Passcode, even if your web app says PIN. In addition, if the account name entered is used from an iOS device you could replace PIN with Passcode. Alternatively you could use both PIN/Passcode and gray out PIN/ if the account name entered have been used on an iOS device lastly.

  • Thanks for the reply, Benny! Although we want to make it as simple as possible for people to get started with the app, it's get slightly complicated as the app deals with finances. That's a major roadblock towards using SSO or OpenID type authentication.
    – Thilak Rao
    Mar 27, 2014 at 13:26
  • @ThilakRao You're welcome. Dealing with financial data puts things in another perspective, since security is a big thing under these circumstances. Mar 27, 2014 at 13:30

If you do good job explaining what the code does and why you need to set it, the naming is of secondary importance. Also, aim for consistency: if you’re calling it “PIN” everywhere else, keep calling it “PIN” in your mobile app as well, even though iOS calls it “Passcode”


When you ask users to set the PIN, do you clarify that it should be 4 digits? If not, that could help users to understand what is requested.

I'm personally against PIN codes. Why can't user set a password? I never remember PIN codes, especially if those are generated for me by some system.


The text in the screenshot says that the feature adds an extra layer of security, but it doesn't actually describe what the feature does / how it works. I think you need someting more specific like:

When enabled, you will be asked to enter your PIN every time you access the application. This extra layer of security helps prevent your personal information falling into the wrong hands.

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