The fundamental key theory which extends the practice of diplomacy and international relations is realism.The key factor in information realism is that it is miles an idea that argues that unsavory moves like struggle fare are necessary gear of statecraft in a less than excellent international and leaders need to use them while it is miles withinside the countrywide interest. This is rational in an internationally in which the survival of the country is pre-eminent. If one’s country ceases to exist because of attack or inner collapse, then all different political goals stop to have tons realistic relevance. Realists have two primary methods for dealing with instability in this context: power balancing and deterrence. Deterrence is based on the potential of substantial aggression, whereas the balance of power is based on political, versatile alliances. For instance, the loose coalition of states that attacked the Islamic State group – states such as the US, Russia, and France – relied on various fair-weather alliances with regional powers such as Saudi Arabia, Turkey, and Iran (Camisão, 2018). Hence, a leader needs to be extraordinarily careful while determining which and while to apply navy strength. It is well worth noting that the US invasion of Iraq in 2003, undertaken as a part of the Global War on Terror, became antagonistic with the aid of using maximum main realists as a misuse of strength that might now no longer serve US countrywide interests (Camisão, 2018).  

 
 The following factor which plays a role in the diplomacy practice in globalization is Marxism. Marxist concepts are all connected by the common goal to contribute to what they perceive as the greater good of humankind and its environment (Pal,2018). Marxism offers a unique perspective on migration, demonstrating that shutting borders is a sociologically and economically ineffective approach in the context of the environment we all live in. Capitalism began a phase of colonial bordering and social reform by wage labor at the same time. By taking a historical and analytical approach to IR, mainstream IR can distinguish those systems. It has examined social classes and seeks to abolish the foreign system's economic structure, claiming that capitalism is no longer practical in the real world. For instance, Singapore, Hong-Kong, South Korea, and Taiwan were known   as the Four Asian Tigers because of their rapid industrialization and high growth rates from the 1960s to the 1990s. In these countries, a strong ruling elite consented to a specific type of financial economy – often called a ‘neoliberal’ model – which also took hold across the world to varying degrees as other states sought to emulate this ‘success’ (Pal,2018). It claims that the growth of capitalism determines or is tied in separate ways to the building of modern boundaries. 

 Another theory of diplomacy and international relations which has played a crucial role in the diplomacy practice of globalization is Liberalism. Liberalism, also known as "liberal internationalism," is founded on the premise that the new global structure will provide a stable world order. Rather than using direct force, such as military action, liberalism emphasizes foreign cooperation as a way of advancing each country's interests. Liberals agree that the costs of using power, such as economic damages and civilian deaths, greatly outweigh the gains. As a result, liberal leaders tend to use economic and social influence to achieve their national objectives for instance, obtaining the agreement of a neighboring country to help secure a border. Economic strategies, such as bilateral trade negotiations and diplomatic diplomacy, would be more useful in promoting political agendas in today's globalized world than threatening force. Realism has begun to fade as a realistic diplomatic policy as democracy has become more entrenched in international collaboration by the creation of institutions such as the United Nations. It may be argued that the western tradition, as perpetuated by the United States, has been the dominant system of international affairs, with well-established principles and international institutions to govern it. 

 Apart from that, Constructivism theory has also been responsible and relevant to the diplomacy practice of globalization. Constructivism is based on the idea that a nation's value systems—historical, spiritual, and cultural its foreign policy efforts and attitudes, rather than the outright pursuit of material interests. Although German invasion was the primary cause of World War II, Germany only sends its military forces outside of its borders when its government is convinced that it is necessary to interfere in cases of violence or confrontation that threatens to spread to other countries. After the first and second Gulf Wars, the country's foreign policy has shown this, the latter of which Germany refused to participate, as well as its reluctant participation in United Nations-led operations in Somalia and Yugoslavia. Constructivists often contend that states are not the most relevant players in international affairs, but that international organizations and other non-state actors can influence action through lobbying and persuasion. As a result, constructivism has become a common and significant philosophy in recent decades, as non-state actors have gained political clout. Human rights are promoted by foreign bodies, who help to make them an international standard to which countries must adhere.  
In conclusion, the factor of globalization has drastically changed the practice of diplomacy and international relations. Diplomacy and international relations theories can help us understand the way the international systems work, as well as how nations engage with each other and view the world. Varying from liberal, equality-centric strategies to straightforward realist concepts, diplomats and international affairs scholars also use international relations models to dictate a government's course of action in response to an international political problem or concern. Professionals in the area can help understand the motivations and priorities that drive strategic choices around the world by researching the following core international theories.