Planetary nebulae are some of the most strikingly beautiful astrophysical phenomena known, gracing many a glossy-paged, coffee-table book and earning them the nickname "cosmic butterflies". Classical stellar evolutionary theory states that all intermediate mass stars should produce a planetary nebula, forming as the star leaves the Asymptotic Giant Branch and evolves towards the white dwarf phase. While it remains the standard for astronomy textbooks, this paradigm has gradually become less and less accepted by the planetary nebula community. As such, it is now clear that a significant fraction of planetary nebulae originate from a binary evolutionary pathway, with some theories even going as far as to say that binarity may be a prerequisite to form a planetary nebula. In this seminar, I will begin by outlining the fundamental pathways for binary evolution and how they each may relate to the formation of planetary nebulae. I will then go on to discuss some of the more interesting developments in the field, with particular emphasis on post-common-envelope central stars and what they can tell us about the common envelope phase itself. Finally, I will discuss the growing connections between planetary nebulae and other binary phenomena including novae and supernovae type Ia.