The marker is a point on Earth beneath the station
The ISS travels around Earth while Earth rotates underneath it. On a flat world map, the marker gives the latitude and longitude below the station. It does not mean the spacecraft is at ground level or that everyone nearby can see it.
The station completes an orbit in roughly 90 minutes. That is a useful scale for understanding how quickly the map changes, not a timetable for repeated passes over your house. Earth’s rotation means that successive ground tracks cross different longitudes.
Altitude, speed and the curved line answer different questions
Altitude describes height above Earth; velocity describes motion along the orbit. Neither is the distance from your own location to the station. A station above a distant coastline can still be far away from an observer whose city looks close on a zoomed-out map.
The curved line is a ground track, a projection of an orbit onto a map. A jump at the left or right edge can be the track crossing the longitude boundary. It is not a sudden reversal of the spacecraft. The plotted future positions are predictions, so later orbit adjustments can change them.
A pass overhead is not always a visible pass
The station is visible by reflected sunlight. Your location can be dark while the station above it remains sunlit, which makes some dawn and dusk passes suitable for observing. Cloud, the height of the pass above your horizon, and buildings or hills also affect visibility.
Use NASA’s Spot the Station with your observing location to plan a sighting. The world map on this site provides orbital context; it does not calculate whether the station will be illuminated and visible from your exact position. The satellite-spotting guide explains how to read a local pass prediction.
Check the age of the position before using it
This site requests positions from Where the ISS at?. A moving interface depends on successful responses from that service and on your network connection. If the display stops updating, treat its last position as historical until fresh data arrives.
For a practical check, compare the position timestamp with your current time before going outside. Then verify the start time, direction and maximum elevation in a local prediction service. Write down which service and time zone you used; that makes a missed sighting easier to diagnose than relying on the map alone.