A first step in understanding on-again/off-again relationships is to describe them. This chapter outlines the definition of these relationships and the collective of descriptive information from the research. Across a variety of college student, community, crowdsourcing, and secondary dataset samples, the research shows that a majority of individuals (approximately two-thirds) experience at least one on-off relationship. These relationships tend to go through two to three renewals on average and last just as long or longer than committed romantic relationships that do not break up and renew. Although the vast majority of breakups are initiated by one partner, about half of the renewals are characterized as mutual. Few sex or sexual orientation differences have emerged thus far, but additional research assessing differences among various age cohorts, cultures, and other demographic factors is needed. This chapter ends with a discussion of why the experience of relationship cycling is likely to continue in today’s dating landscape.