Secular evolution gradually shapes galaxies by internal processes,in contrast to early cosmological evolution which is more rapid. Animportant driver of secular evolution is the flow of gas from the disk into the central regions, often under the influence of a bar. In this chapter we review several new observational results on barsand nuclear rings in galaxies. They show that these components areintimately linked to each other and to the properties of their hostgalaxy. We briefly discuss how upcoming observations, e.g., imaging from the Spitzer Survey of Stellar Structure in Galaxies (S4G), will lead to significant further advances in this area of research.