Transposable elements are DNA sequences that have the ability to move or "transpose" themselves within a genome. They make up a significant portion of eukaryotic genomes, and are thought to have played a major role in shaping genome structure and function over evolutionary time. There are two main types of transposable elements: retrotransposons, which use a "copy-and-paste" mechanism to move within the genome via an RNA intermediate, and DNA transposons, which use a "cut-and-paste" mechanism to move directly within the genome. Transposable elements can have both positive and negative effects on the host organism. On one hand, they can contribute to genetic diversity and evolution by promoting genetic rearrangements and facilitating the spread of beneficial traits. On the other hand, they can also cause mutations, disrupt gene function, and contribute to genetic instability and disease. Research on transposable elements aims to understand their roles in genome evolution, gene regulation, and disease, as well as to develop tools and techniques for studying and manipulating these elements in a variety of organisms.