Part IV (Articles 36-51) contains the Directive Principles of state policy . These principles underline the philosophy of democratic socialism with a touch of Gandhian idealism as incorporated into the fundamental law of our country. 
It came from the Irish constitution, which derived from the Spanish constitution. The realistic component is to be seen in the need to reflect in depth on the state 's basic mission and the overall consequences of such a mission, as well as the policy criteria for fulfilling it.. The framers of the Indian constitution were thinking , not merely in terms of setting up a legal constitutional framework , on the principles of political democracy but also of going beyond it in planning to use the constitution as instrument of social change. The DPSP are directly connected with the preamble , and paraphrase the objectives laid down there in clear terms. The articles included in part IV of the constitution contain certain directives it shall be the duty of the state to follow both in the matter of administration as well as in the making of laws.
Classification and scope of Directives-
The Directive principles of the constitution of India are a unique blend of Socialism, Gandhism , western liberalism , and the ideals of the Indian freedom movement.
Article 36 clearly directs the state to secure and protect a social order which stands for the welfare of the people.
Article 37 says that Directive principles are not justiciable but are fundamental to the governance of the country and the state has the duty in applying the directive principles of state policies.
Implementation of DPSP-
Since the commencement of the constitution , there have been a number of legislations to implement in DPSPs. The very first Amendment act was for implementing land reforms. It was followed by the 4th , 17th , 25th, 42nd and 44th amendment act (1992) is in pursuit of implementing Art. 40. There have been several factory legislation to make the conditions of work humane for the workers. The development of cottage industries was one of the key aspects of the government's economic policy and for that reason the commission of the khadi and village industries exists. The governments' stance on matters relating to the uniform civil code.
Features of Directive Principles of state policy-
1. DPSP are non –justiciable- The opening article of the Directive Principles, Article 37, specifically declares ‘The provisions contained in this part shall not be enforceable by any court’ .
2. The Directive principles are positive directions to state to act in a particular manner- Article 37 says that they are ‘nevertheless fundamental in the governance of the country and it shall be the duty of the state to apply these principles in making laws.
3. The Directive principles lay down the various tenets of a welfare state- The concept of welfare state is a synthesis between total state control of socialism and the blind pursuit of profits of liberalism .
Relation between fundamental rights and directive principles –
1. The Supreme court in various cases has evolved a ‘ Doctrine or theory of harmonisation’
2. It has further stated that both the fundamental rights and the directive principles are in fact supplementary to each other and together constitute an integrated schemes.
3. It has also held that where this is not possible , the fundamental rights shall prevail over the Directive principles.
4. The present position is that only article39(b) and article 39(c) can be given precedence over Article 14,19 and not all the directive principles .
 https://knowindia.gov.in/profile/directive-principles-of-state-policy.php.  https://www.yourarticlelibrary.com/policies/implementation-of-the-directive-principles-of-state-policy-in-india/5499.  http://www.eenadupratibha.net/Content/PublishFiles/0099CABF-F89E-4780-BC69-D2A9AFF849C2/start.html.  https://www.toppr.com/ask/question/explore-the-relationship-between-fundamental-rights-and-directive-principles/. References- 1. https://www.mea.gov.in/Images/pdf1/Part4.pdf. 2. https://shodhganga.inflibnet.ac.in/jspui/bitstream/10603/75392/15/15_summary.pdf. 3. https://byjus.com/free-ias-prep/directive-principles-of-state-policy/. Author- Aeshna Raghuwanshi, Content Writer, Legal Eagle.