Published in "Galactic and Extragalactic Radio Astronomy", 1988, 2nd edition, eds. G.L. Verschuur and K.I. Kellermann.

For a PDF version of the article, click here.

Table of Contents

INTRODUCTION

The Role of Neutral Hydrogen in Galaxies

The Information in the 21-cm Line

Pictorial Presentation of HI Data

THE DISTRIBUTION OF HI IN GALAXIES

Morphology

Sizes

Warps

Appendages

VELOCITY FIELDS

Rotation Curves

Distortions in the Velocity Field

The Mass Distribution in Spiral Galaxies

Dark Matter in Dwarf Galaxies

THE VELOCITY WIDTH AS A DISTANCE INDICATOR

The Velocity Width-Magnitude Relation

Deviations from Hubble Flow

HI CONTENT AND OTHER GLOBAL PROPERTIES

Relations Between Global Properties for Spirals (Sa and Later)

Content of Early-Type Galaxies

ENVIRONMENTAL EFFECTS

Tidal Interactions

Gas Deficiency in Cluster Spirals

COSMOLOGICAL STUDIES

21-cm Redshift Surveys

Voids and the Segregation of Galaxian Properties

HI in Active Galaxies

HI in Quasars and in Their Spectra

REFERENCES