Formation mechanism of massive stars (> 8 Msun) is an outstanding issue in astrophysics. It is still unknown how a massive star gains that much mass in a short time of about a Myr. This long standing puzzle about the formation of massive stars remains unresolved mainly because of their rarity, fast evolution and elusive pre-main sequence phase. Several theories have been proposed to describe the formation mechanism. Here, I shall briefly describe two theories (viz., Cloud-cloud collision and filamentary accretion) that are getting attention of the community because of their increasing observational evidences. Recently, we also found signatures supporting these two theories towards two star-forming regions, and these results will be discussed in a greater detail in my talk.

Towards the end of the talk, I will briefly discuss a couple of projects carried out by me with TIRSPEC and TIRCAM2 instruments mounted on the 2-m HCT and 3.6m DOT, respectively. Finally, I shall also discuss the projects that I would like to pursue at ARIES using the available observing facilities.