**1. Introduction**

Corrosion is the naturally happening process which transfers metals into their stable form. Metals easily facilitated to the corrosion in the presence of corrosive media (acidic, basic, and brine). In other words, it is the gradual deterioration of metals in the existence of favorable reactive environment. Nowdays, corrosion of metal became global problem as it worsened the quality of metals and directly or indirectly affect economy of any country. The control of corrosion metals using appropriate methodology is so important. Application of corrosion inhibitor for the prevention of corrosion found prominent attention. The suitable concentration of corrosion inhibitor reduced the corrosion rate without altering the concentration of corrosive media [1]. For the control of metal corrosion, various kinds of inhibitors including inorganic compounds, plant extract, and organic molecules are commenced for the mitigation of metal corrosion as illustrated in **Figure 1** [2]. Small organic inhibitors are widely applied for the control of metal corrosion as they are easy to prepare compared to complex organic molecules [3]. The best example of small organic molecule as corrosion inhibitor is a BTA [4]. BTA effectively mitigated metal corrosion. The presence of unique functionality in the small organic compounds is strongly react with metal by chemical or physical bonding and preserved metal against harsh corrosive media. Corrosion inhibitors interact with metal at metal/solution interface by forming film on the metal surface and hindered corrosion reaction. The formed protective

**Figure 1.** *Classification of corrosion inhibitor.*

film limits corrosive media, oxygen, and water diffusion toward metal surface, so reducing corrosion rate. Any type of corrosion inhibitors can be categorized into cathodic, anodic, or mixed type which depending on their influence in the suppressing cathodic/anodic reaction or both [5]. This chapter includes the application of small organic molecule for the prevention of corrosion of various metals in different corrosive media. This chapter includes the application of small organic molecule for the prevention of corrosion of various metals in different corrosive media.
