This chapter collection explains how the Square Kilometre Array (SKA) can help us trace how gas and dust move through our Galaxy — from cold clouds where stars form to the shocks and winds created when stars die. The authors argue that new radio data, taken over wide areas with high sensitivity, high spectral detail, and precise positions, can reveal processes that are hard to see at other wavelengths.

The paper is an overview by the SKA Our Galaxy science working group. Rather than presenting a single new observation, it summarizes planned studies and the kinds of measurements the SKA1-Mid and SKA-Low arrays can do. These include very high angular resolution (down to arcseconds or a few hundred astronomical units in some cases), high surface‑brightness sensitivity, and full polarization and spectral capability. The chapter points to more detailed proposals in separate contributions that focus on specific phases of the interstellar medium and stellar evolution.

Several concrete survey ideas are described. One proposal is a Galactic plane radio continuum survey covering about 6302 square degrees nominally between 10 and 15 GHz, with angular resolution that would resolve structures smaller than 0.05 parsec out to 20 kiloparsecs. Other focused plans include deep maps of the Galactic centre over a 2.0°×0.4° region around Sgr A* at 1.36, 6.55 and 11.85 GHz, and studies of the cold neutral medium (CNM) at scales near 1,000 astronomical units. The authors also highlight radio recombination lines (RRLs) as extinction‑free probes of the warm ionized medium, which holds most of the Galaxy’s ionized hydrogen and whose temperatures, densities and motions can be measured across many scales.

Magnetic fields and small dust grains are two specific science targets. The SKA can attempt Zeeman measurements — a change in spectral lines caused by magnetic fields — to estimate field strengths in clouds and disks. Zeeman detections in diffuse clouds are rare today, so the authors stress that large, statistical surveys are needed to judge how important magnetic fields are in regulating star formation. Complementary probes include dust polarization (which traces the magnetic field direction on the sky) and synchrotron emission (radio light from energetic electrons), which can help test how cosmic rays penetrate dense gas. Another topic is the anomalous microwave emission (AME), an excess between about 10 and 60 GHz thought to come from very small, rapidly rotating dust grains; SKA maps could help distinguish that spinning‑dust idea from alternative explanations.