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ABSTRACT. Some selected aspects of current research into active galactic nuclei (AGN) are reviewed. Included topics are the continuum, the broad emission line region and the existence of black holes in galactic nuclei. It is found that an increasing number of observations indicates the presence of accretion disks around massive black holes.

Key Words: active galaxies, black holes, accretion disks, variability, broad line region

Table of Contents

• INTRODUCTION
• THE CONTINUUM
• The IR Continuum
• The Optical-UV Continuum
• The X-ray Continuum
• The Soft Excess
• The Hard X-ray Power Law
• X-ray Reflection and Absorption
• The -ray Continuum
• THE BROAD-LINE REGION
• Observational Methods
• The Standard BLR Model
• Recent Developments
• The NGG 5548 and 4151 Campaigns
• The Accretion Disk Model
• THE CENTRAL BLACK HOLES IN ACTIVE GALACTIC NUCLEI
• Formation
• Methods of Inferring the Mass
• CONCLUSIONS
• REFERENCES