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Article Contents

ABSTRACT

1.INTRODUCTION AND PURPOSE

2.ABUNDANCES FROM HII REGIONS

2.1.It's All in Osterbrock

2.2.Emission Line Abundances for Beginners

2.2.1.The Direct Method

2.2.2.The The Bright Line (or ``Empirical'') Method

2.2.3.Photoionization Modeling

2.3.Abundances: Uniformities and Uncertainties

3.SIMPLE CHEMICAL EVOLUTION

3.1.Introduction

3.2.Absolute Abundances: Some Simple Formulae

3.3.Relative Abundances

3.3.1.Nucleogenesis Differences

3.3.2.Time Delays

3.3.3.Changing Yields

4.ABUNDANCE PATTERNS IN DWARF GALAXIES

4.1.Uniform Abundances?

4.2.The Metallicity-Luminosity Relationship

4.3.Relative Abundance Patterns

4.3.1.C/O

4.3.2.N/O

4.3.3.S/O

4.3.4.Si/O and Fe/O

4.4.Environmental Effects?

5.ABUNDANCE PATTERNS IN SPIRAL GALAXIES

5.1.Radial Gradients

5.2.The Metallicity-Luminosity Relationship

5.3.Relative Abundance Patterns

5.3.1.N/O

5.3.2.S/O

5.4.Environmental Effects?

6.SELF-CONSISTENT STAR FORMATION HISTORIES

6.1.Star Formation Histories of Dwarf Irregular Galaxies

6.2.Example 1: The Sextans A and Pegasus Dwarf Irregular Galaxies

6.3.Example 2: IZw18

7.SUMMARY

REFERENCES