Much has been learned about extrasolar planets in the past 20 years. An overview of the status of the research is presented, addressing exoplanet detection, planet formation and orbit migration, and issues that challenge current theories. Though the observational evidence of extrasolar planets is good in many cases, there are some difficulties in the analysis of the data and limitations of the methods. Extrasolar planetary systems often are very different from our own planetary system. Many known exoplanets are located closer to their stars than Mercury is to the sun. This has prompted development of theories for the migration of planet orbits. Migration theories have challenges in explaining why so many exoplanets have not spiraled into their star and have difficulty explaining exoplanets with orbits that are inclined compared to the equators of their stars. Recent reports from some researchers have expressed concerns that a surprising percentage of transit detections of exoplanets could be due to eclipsing binary stars or brown dwarf stars rather than exoplanets. Another challenge is the large radii of many so-called "hot Jupiters." Known mechanisms may not be adequate to explain the sizes of these planets. Though there is much interest in finding evidence of habitable extrasolar planets, there is still no clear evidence that any exist. The meaning of "habitable zone" is discussed in relation to extrasolar planet research. Extrasolar planets can be understood as being created on the fourth day of the creation week rather than forming from protoplanetary disks.