  Based on works of Saharon Shelah, Jakob Kellner, and Anda T\u{a}nasie for
controlling the cardinal characteristics of the continuum in ccc forcing
extensions, in the author's master's thesis was introduced a new combinatorial
notion: the intersection number for forcing notions, which was used in such
thesis to build a general theory of iterated forcing using finitely additive
measures. In this paper, we present the definition of such a notion and prove
some of its fundamental properties in detail. Additionally, we introduce a new
linkedness property called $\mu$-intersection-linked, prove some of its basic
properties, and provide some interesting examples.
