Why doesn't my tracker show up on the Internet?
Traffic from an ArduinoTrack (or any APRS transmitter) will not always show up on the Internet. This can be caused by several issues. Read More for a full description of how iGating and Digipeating work.
The packets from the ArduinoTrack are typically broadcast out across a common channel (144.390MHz). There are several types of stations that are also on that frequency such as other beacons, Digipeaters (stations that "repeat" anything they hear back out on the same frequency), iGates (stations that "gateway" anything heard to the Internet).
Beacons are what they are. Other than you're competing with them for bandwidth, they don't have any impact on you, either positive or negative.
Digipeaters are the stations typically set on top of large towers who's purpose in life is to extend the range of a small/low-powered transmitter. So for instance, if you lived in a large-ish city, and you wanted to watch your friend riding his bicycle on the opposite side of town, you would utilize a Digipeater somewhere near the path of his bike, and that Digipeater would re-transmit his positions across the entire city. You could just receive the packets directly, but you'd have to have a good tall receive antenna and a little luck to hear him from the other side of town.
Now, there are some beacons that specifically don't want to be Digipeated because their signal is too strong, or too un-important to waste the common bandwidth of being heard, and then to be re-transmitted back out on the same channel. This might be a local weather station that already has a decent transmit coverage, or in your case, it would be a balloon that is 5+ miles up in the atmosphere and already has a radio range of tens/hundreds of miles. That's why I incorporate the Disable Path Above feature, because there is no point in Digipeating traffic from a balloon that is high in the sky.
However, when the balloon is on the ground, or near the ground, it is often desirable to take advantage of the extra radio coverage of Digipeaters, and so that's what the WIDE2-1 path is for. WIDE2 is a special "callsign" of most Digipeaters, and the -1 SSID means to re-broadcast this station once. (Technically you could set WIDE2-2 or WIDE2-3 and be linked out 2 or 3 times, although that's strongly discouraged).
Regarding the iGates, they don't care what your Path is. They typically are set up to gate anything they hear from the radio receiver, onto the Internet.
So, for your example, if you drive an ArduinoTrack close to an iGate (typically within 1 mile on the ground), the position will be registered on the Internet on sites such as APRS.fi. That will be true regardless of your path.
Alternatively, if you have your path set up as WIDE2-1, and you drove close to a Digipeater, then your beacon would be Digipeated across a large area, and probably (but not necessarily) be iGated by another iGate station onto the Internet. Sometimes the Digipeaters and the iGates are one in the same, but not always. Often the Digipeater is a small box that is borrowing space on top of a tower, and relies on a home station with Internet access to do that iGating.