The "bases" in dating are a metaphor derived from baseball to describe different levels of physical intimacy between partners, progressing from least to most intimate. The traditional understanding of the four bases is as follows:

• First Base: Kissing and making out, often including French kissing (open-mouth kissing)

• Second Base: Touching above the waist, typically involving intimate touching or fondling of the breasts and nipples, either over or under clothing

• Third Base: Stimulation below the waist, such as manual or oral stimulation of the genitals, including oral sex

• Fourth Base (Home Run): Sexual intercourse, involving penetrative sex

This metaphor has been used for decades as a discreet way to talk about physical milestones in a relationship. However, modern perspectives emphasize that relationships and intimacy do not always follow a linear path and encourage open communication, consent, and respect for boundaries rather than strictly adhering to these stages

. Additionally, some modern interpretations expand beyond physical intimacy to include stages of emotional connection and relationship development, such as attraction, reality testing, working through differences, commitment, and deep attachment

. In summary, the bases in dating traditionally map out escalating levels of physical intimacy, but healthy relationships prioritize mutual consent, communication, and emotional connection alongside or beyond these physical milestones.