On a recent Saturday, I had my hands full of bags at the 34th Street/Herald Square subway station and couldn't reach for my MetroCard without putting everything down, so instead, I pulled out my phone and initiated a payment by tapping it on one of those high-tech OMNY readers.

Would it work? Would I get double-charged? I did it. It worked and it worked quickly. I walked through without incident and there were no double-charges.

A few days later, I pulled out my credit card with a contactless chip in it and tried that (despite being slightly uncomfortable waving my credit card around). It also worked flawlessly and, of course, no one snatched my card away.

By now, straphangers have seen the ads inside trains alerting them that they can now use their phones, credit cards and even their smart watches to pay subway fare. But since the program hasn't been completely rolled out yet, not every station has the OMNY readers so commuters haven't had to deal with them yet.

So to help you get a better understanding, we've answered some common questions you may have.

So, what does OMNY stand for, anyway?

It's an acronym for "One Metro New York" that plays off the word "omni," meaning "all."

How does it work?

Instead of swiping a card, which can be very frustrating when your card has seen better days, you'll simply tap your smart phone, smart watch (even a Fitbit) or a single contactless chip credit or debit card (which has a symbol on it). If you use a smart device, you'll have to have a credit card linked to it beforehand for it to work.

The reader won't tell you your fare, so you'll have to look on your credit card statement to see how much you were charged, otherwise you can see it by signing up for an OMNY account. You can sign up at omny.info/register for free.

Can I switch between a contactless card and my smart device?

Yes, but only one payment method can be used at a single time and you must use the same credit or debit card you first used to get free transfers.

Do I have to make an OMNY account?

No, unless you'd like to access your trips and charges in one place.

Where are the OMNY taps right now?

They can be found at nearly 180 subway stations, with 60 added in January, including at major hubs—Herald Square, 47-50 Sts-Rockefeller Center, Bryant Park, West 4 St-Washington Square, World Trade Center and Jay St-Metro Tech—with more added along the 2/5 and 6 lines in the Bronx in February.

The most recently added readers service the B and D lines from 145th St to West 4 St-Washington Sq.; the F and M lines between 47-50 Sts-Rockefeller Center and West 4 St-Washington Square; the A and C stations from Inwood-207 St and down Eighth Avenue in Manhattan to Jay St-MetroTech, respectively; and the E lines from 50 St to the World Trade Center.

The MTA is currently rolling out OMNY to bus routes and Staten Island Railway locations as well. In 2021, it will extend to the Long Island Rail Road and Metro-North Railroad.

Here's the latest released map:

Photograph: MTA

Why the change?

It turns out the NYC is behind other major cities in terms of up-to-date public transit payment options. London's tube has had the Oyster Card, Boston's T has had the CharlieCard and Tokyo has had the Suica for years. It's about time this progressive city got on board.

When will OMNY be in full swing?

The roll out was slated to happen between 2019 and 2023, so you'll see more and more readers going up at subway stations across the city. By 2023, you'll have to use OMNY.

What if I don't want to?

Luckily, until 2023, you can use MetroCard and eTix. After that, there won't be a choice.

Can I pay with cash then?

By 2021, the MTA will have contactless transit cards you can put cash on, much like you do now for the MetroCard, and it'll be available for purchase from retailers and OMNY vending machines.

What about my reduced fair card and my unlimited ride pass?

Unfortunately, the current OMNY system doesn't provide monthly or student discounts, so every tap will cost the standard $2.75 per ride, but as the system expands to different boroughs and achieves saturation these pricing options will be added.