"Well, the first thing to say is that we've worked hard to maintain compatibility, so that any program written with an earlier version of Mathematica can run without change in 3.0, and any notebook can be converted"

This quote by Stephen Wolfram is describing the 3.0 variation of Mathematica, a software program used for technical computing. Wolfram is highlighting the importance of compatibility between the 3.0 variation and earlier variations of Mathematica. He is saying that any program written with an earlier version of Mathematica can run without change in 3.0, and any notebook can be converted. This means that users of the 3.0 version of Mathematica will not have to reword their programs or note pads in order to use the new variation. This is a great benefit for users, as it permits them to continue using their existing programs and notebooks without needing to start from scratch. Wolfram is highlighting the importance of compatibility in between versions of Mathematica, which is a terrific advantage for users.