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Some of the foundational procedures of modern biology are the extraction and characterization of DNA from various cultures and tissues. This chapter guides the reader through the key principles of DNA extraction using some of the most commonly needed procedures, including preparation of (1) plasmid DNA from bacterial cultures; (2) plant genomic DNA; (3) plant genomic DNA using a commercial kit; (4) animal genomic DNA using organic solvents; and (5) DNA fragments from agarose gels. After each extraction approach, characterization of the quantity and quality of the extracted DNA is about the same. As primary examples, we cover the characterization of extracted DNA using a spectrophotometer as well as fluorometric measurements. To verify the integrity and size of the extracted DNA, gel electrophoresis remains as the most commonly used approach. Consequently, we have included a basic protocol that uses an alternative sodium borate electrophoresis buffer. The combination of reliable extraction procedures with efficient characterization steps allows downstream biological procedure to be performed successfully.