A logo design is really a graphical element (ideogram, symbol, emblem, icon, sign) that, along with its logotype (a exclusively set and arranged typeface) form a hallmark or business brand. Typically, a logo design is perfect for quick recognition. The logo design is a component of a company’s commercial brand, or economic or academic entity, and it is shapes, colors, fonts, and pictures are frequently not the same as others inside a similar market. Logos are also used to identify organizations and other non-commercial entities.
In logo designing you need tools and more you need is imagination and understanding of product or company of which you are designing a logo. I have compiled 35 logo designing tutorials to get the better understanding. This article covers use of Photoshop to design a logo.
I have mentioned the download links of source files too if those were provided by designers.
reference：http://pelfusion.com/35-logo-designing-photoshop-tutorials/