Do all flight tracking software and websites offer live, up-to-the-minute flight information?

All of the most popular flight tracking websites feature real-time flight tracking. Tracking sites are able to provide this information using satellite and radar data.

Though flight tracking data is advertised as real-time, the term "real-time relevant to when the data is received" is often added because there is always a slight delay in receiving some data. This is because, although it is possible to track flights using real time data, it is not possible to receive real-time information from them. Information received from satellites and radars must first be relayed via the satellite or radar device and then retransmitted.