Transcription activator-like effectors (TALEs), first identified in Xanthomonas 
bacteria, are naturally occurring or artificially designed proteins that 
modulate gene transcription. These proteins recognize and bind DNA sequences 
based on a variable numbers of tandem repeats. Each repeat is comprised of a set 
of ∼ 34 conserved amino acids; within this conserved domain, there are usually 
two amino acids that distinguish one TALE from another. Interestingly, TALEs 
have revealed a simple cipher for the one-to-one recognition of proteins for DNA 
bases. Synthetic TALEs have been used to successfully target genes in a variety 
of species, including humans. Depending on the type of functional domain that is 
fused to the TALE of interest, these proteins can have diverse biological 
effects. For example, after binding DNA, TALEs fused to transcriptional 
activation domains can function as robust transcription factors (TALE-TFs), 
while fused to restriction endonucleases (TALENs) can cut DNA. Targeted genome 
editing, in theory, is capable of modifying any endogenous gene sequence of 
interest; this can be performed in cells or organisms, and may be applied to 
clinical gene-based therapies in the future. With current technologies, highly 
accurate, specific, and reliable gene editing cannot be achieved. Thus, 
recognition and binding mechanisms governing TALE biology are currently hot 
research areas. In this review, we summarize the major advances in TALE 
technology over the past several years with a focus on the interaction between 
TALEs and DNA, TALE design and construction, potential applications for this 
technology, and unique characteristics that make TALEs superior to zinc finger 
endonucleases.