Newbie would like to know what open jaw flights are.

(Edit: I didn't see Jeff's explanation when I wrote this.)

Here's a hypothetical example of an open jaw flight:

Seattle to Vienna
Paris to Seattle

The hypothetical traveler would start their trip in Vienna and end up in Paris. In other words, they would get from Vienna to Paris by some kind of surface transportation. Once in Paris at the end of their trip, the traveler would save the time of having to back-track from Paris back to Vienna. The cost might be the same, more, or less--you have to price it both ways, adding in the cost of getting back to Vienna from Paris. But in this example, there would definitely be a savings in time, and there might be a savings in cost.

Now that the "what" is covered, maybe it would be useful to describe the "how." Using a search engine, such as skyscanner or kayak, you select the multi-city option for your search and just plug in the dates and destinations. You could then compare the cost of the multi-city fare + the cost of connecting the dots within Europe vs. a round trip to/from US + travel within Europe which is likely to include backtracking. See what works out best cost-wise and also consider what your time is worth.

Emily, does Skyscanner have a multi-city option? I've never seen one. If I'm wrong please correct me and let me know how to do it. On Skyscanner I've always just plugged in two separate one-ways to get an approximate cost of doing an open-jaw.

Skyscanner doesn't offer a multicity option right now per their FAQ. Kayak and Google Flights (and their techie side ITA Matrix) do.

The nice thing about doing an open jaw route is that not only can you use trains to travel intra-Europe, you can also take advantage of the European LCCs (or European legacy carriers price matching the LCCs. BA on the same routes as easy jet is often quite competitive and often cheaper once you have the baggage factored in) on a multicity trip for far cheaper than trying to do it all on a single ticket.

Thanks selkie. I've seen several people on here recommend using Skyscanner to find multi-city flights and I always wondered if I was missing something. Guess they just never tried it themselves and assumed it was possible.

Even airline reservation sites like United, American and Delta allow for multi-city or multiple-city bookings:

https://www.united.com/web/en-US/apps/booking/flight/searchMD.aspx?CS=N

http://www.aa.com/reservation/multiCitySearchAccess.do?anchorEvent=false&tripType=multi&netSaaversTripType=

http://www.delta.com/air-shopping/searchFlights.action?tripType=MULTICITY

Yes, no multi city option on skyscanner. I have used it, however, as described above as separate one ways.

Edit - to clarify, i would not buy two one way tix;; what I descr above is just to get a feel for cost. I should emphasize that Kayak is my go to flight search engine. I tend to use sky scanner for travel within Europe only.

"And also, explain why they are less expensive than flying within Europe to return back to the states?"

They may or may not be cheaper, but they have two very important advantages.

1) If you buy a trip all on one ticket (say, Seattle to Paris and Berlin to Seattle, connecting in London in both directions), you are "protected" if you miss a connection through no fault of your own. The airline will put you on the next available flight at no charge (key word is "available" since flights can be full). But if you arranged your own flight from Berlin to London and don't get to London on time, for ANY reason, the airline is not responsible if you miss your London to Seattle flight. You would then potentially have to buy a last minute one way London to Seattle ticket - a very expensive proposition.

2) If you are all on one ticket and have checked luggage, the airline will transfer the luggage, saving lots of time and aggravation. If you are on separate tickets, these days most airlines won't transfer ("interline") the luggage. You have to wait to claim your bags, then wait to recheck them.

To find open jaw flights, be sure to use the "multi city" option on websites. Don't look for two one-way tickets, as that's usually much more expensive.

Let me provide you with a current example of RT and open jaw pricing. We are in the process of planning a Turkey tour with a university alumni group. We prefer to book our own air fare since we like to go early and come back later. We are going mid Sep through the second week or so of October.

Round trip air offered by the tour company from Denver to Istanbul and home from Ankara - $1400
Round trip to Istanbul and back to Denver $1068
Denver to Istanbul and home from Ankara $1146
Denver to Istanbul, Ankara to Amsterdam for four days, home to Denver $1450

Open jaw tickets do not just have to be two legged trip (out and back) you can add other stops for a very reasonable price. Since I haven't priced it I don't know what the cost for a local flight from Ankara to Istanbul would be but doubt if it would be less than the $78 difference. And all of this is on one ticket so if anything goes wrong with a missed or delayed flight, it is the airline's responsibility to get me to my end journey. Almost all of our travels are via open jaw and sometimes we stick in extra stops at modest prices.