One of the most important and core activities of the Human Resource department is cleary recruitment. Defined as the process of attracting, interviewing and selecting the right candidate for certain vacancy, recruitment is considered to be carried out generally by managers or hiring experts -people hiring people, through the identification of main skills, experience and fitness of the candidates with the job and with the company. Nowadays, with the technology going further and more areas of the company adopting computing processes, the recruitment tasks have been also relied in software and algorithms which help locating and identifying potential candidates.With massive amounts of Personnel data available in the organisations referred as Big Data,companies can improve methods like talent acquisition,development and overall organisational performance. Using Big Data in HR thoroughly involves monitoring performance metrics, external criterions and social media data to deliver a more informed solution.Big Data is very fast and demanding so new tools are required to make more smart and intelligent decisions.The potential to evaluate Big Data has enabled companies to increase their revenue by innovative business methods to precisely target customers and cut the cost.In order to identify the right candidate, a manager or a hiring expert would usually look for some specific skill, experience or qualification within a limited database of resumes or the defined recruitment source, then select a few finalists, start with the interview process and finally hire or not the person due to the fitness to the vacancy. Something similar happens with the technological tools for hiring called Applicant Tracking System or ATS. ATS uses algorithm similar to search engine optimisation to rank resumes in the search results from the database in any format.This capability uses the job requirement as keywords to find the preferred applicants.The recruiter can use ATS to scan the entire database to obtain candidates with favoured qualifications.A resume that contains more nominated keywords will be positioned higher. ATS also use knock out questions to filter out applicants that doesn’t meet minimum criteria. ATS softwares differ depending on the structure and complexity of the algorithms.Factors like cost,automation and accessibility of ATS are accessed to select the apt software.As any dawn breaks into dusk ATS has both merits and demerits.On the bright side it can help in processing multiple candidates,shortlisting,accumulating resumes,connecting with candidates and vendor management but since ATS uses perfect optimisation ,it may miss out experienced candidates,for instance workers that are changing careers.Another drawback of ATS is that they are keyword dependent.Candidates without prefect keyword on their profiles are missed out.In brief a well -configured ATS may help employers of every size more efficiently and accurately identify qualified candidates, saving them time and money. Some of the top ATS softwares are Taleo,iCIMS,Ultipro and Silkroad.