Recent achievements in magnetic transmission soft X-ray microscopy are reviewed. The magnetic contrast is given by X-ray magnetic circular dichroism, i.e., the dependence of the absorption coefficient of circularly polarized X-rays on the projection of the magnetization in a ferromagnetic system onto the photon propagation direction. A lateral resolution down at 25 nm is provided by Fresnel zone plates used as optical elements. Recording the images in varying external magnetic fields, inherent chemical specificity, a high sensitivity to thin magnetic layers due to the large contrast, and the possibility to distinguish between in-plane and out-of plane contributions allows detailed studies of magnetization reversal processes in magnetic patterned elements and thin films. Micromagnetic simulations support the experimental findings. The potential to study spin dynamics will be briefly outlined.