Elon Musk announced plans to use a giant spaceship and rockets to send humans around the Solar System. According to him, humans should be able to colonize Mars within the next two centuries. Initially, the plan was to send people to Mars, but that has now changed. What was called the Mars Colonial Transporter has now been renamed to the “Interplanetary Transport System”.
The name change here is intentional as now he wants to be able to send people right around the Solar System, with the trip to Mars expected to take 80 days. The Interplanetary Transport System is based on four components, which is why he calls it a system now. The four parts are the rocket, the spaceship, a refueling tanker, and propellant depots.
The most important of those four parts, as unlikely as it seems, are the propellant depots. In order to make the journey viable, the ship has to carry as little fuel as possible. The only way to make that work is if it only needed to carry fuel to get to the destination. Once there, the ship will be refueled using the depot and then it can either move on to the next leg of the journey or return to Earth. The extension of this idea is that planets like Mars will be able to produce the Methane gas needed locally, which means that there will need to be infrastructure on each hopping point along the way.
It is very little in terms of details. In addition, there is no information on what effects being out in space for so long could have on humans. At the very least, Musk has promised that the ride will be fun.