This thesis is centered around particular lines of the triangle. It unifies and describes in detail characteristic lines of the triangle by listing their definitions and key theorems along with stating and proving their basic properties with accompanying illustrations of certain cases. The work is divided into four chapters with each chapter focused on a specific group of significant lines of the triangle. As an introduction, historical context and motivation for their further study there are biographical sketches of mathematicians who are credited with their discovery at the beginning of each section. The lines that are considered in the first two chapters are Euler's line and Wallace-Simson's line. Furthermore, the third chapter includes lines such as Nagel's line, Gauss' line, orthic axis and the line connected with the bisectors of external angles of the triangle. The last chapter of the paper is dedicated to the lines whose existence is ensured by the fundamental theorem of projective geometry, Desargues' theorem. In that chapter, Desargues' theorem is connected with lines such as Gergonne's line and Lemoine's line.