The DNA-binding domain of TALEs (transcription activator-like effectors) from Gram-negative plant-pathogenic Xanthomonas bacteria has become an important tool for the programmable and specific targeting of DNA. Natural TALEs function as transcription factors which are injected via a type III secretion system into plant cells to support bacterial colonization of host plants. TALE proteins bind to DNA via near-identical tandem repeats of 34 amino acids. We solved the “TALE-code” and showed that each repeat recognizes one base in the target DNA sequence via repeat-variable diresidues (RVDs). The simple and modular repeat architecture allows rearrangement of TALE repeats to generate artificial TALEs with virtually any tailored DNA-binding specificity. Highly specific genome-editing TALE nucleases can be engineered for targeted mutagenesis in plants and other eukaryotic organisms. Understanding TALE specificity now also allows to predict target sequences of TALEs in plant genomes to identify their elusive virulence targets. I will present RVD specificities, plant targets, as well as the design of programmable gene switches and programmable precision mutagenesis tools. TALEs are versatile virulence factors for the bacterial pathogen and exceptional tools for biotechnology.