Track and Vertex Reconstruction in ATLAS

High track densities and event rates in the very precise tracking devices of the ATLAS Detector at the LHC put stringent demands on the track and vertex reconstruction software in terms of performance, speed and maintainability over the experiment’s lifetime. With this complex problem in mind the track and event reconstruction software in the ATLAS inner detector has been recently re-structured and extended, implementing a new, highly modular approach based on a global ATLAS event data model. The current reconstruction chain has been prepared for dealing with real data by validating its performance on simulated LHC collisions as well as participation in various detector commissioning programmes. This document gives an overview of the ATLAS tracking and vertexing algorithms and their performance as well as several underlying software aspects which are both essential for fully exploiting the data from the ATLAS inner detector.