In the Constitution of India, Article 1 describes the territory of India. As per article 1, there are three types of Indian Territory; territories of the state, Union territories, and third one is the territory to which the Government of India can acquire at any time.
Talking about Union Territories, they come under the direct Administration of the Central government and controlled by an administrator known as Lieutenant Governor, who is appointed by the President of India. Currently there are 28 States and 8 Union Territories in India.

The concept of Union Territories was introduced in the State Reorganization Act, 1956 through the 7th amendment of the Constitution.
After the Jammu and Kashmir Reorganization Act, 2019 was passed in the Parliament Jammu and Kashmir reconstituted into two separate Union Territories;
Union Territory of Jammu and Kashmir
Union Territory of Ladakh.
In 2020, another Union Territory was formed by merging Dadra and Nagar Haveli and Daman and Diu.Currently India has 8 UTs named;
Andaman and Nicobar Island (Port Blair), Chandigarh (Chandigarh), Dadra and Nagar Haveli and Daman and Diu (Daman), Delhi (Delhi), Jammu and Kashmir, Ladakh, Lakshadweep (Kavaratti), Puducherry (Puducherry). Here it should be noted that;
Territories with small areas, and not capable to sustain its cultural diversity and geographical identity are considered for the special protection. There are varied reasons behind the creation of Union Territory which can be understood here with examples.
As the administrative authority of a state is known as the Governor, for Union Territory, a Head is appointed by the President, who is designated as lieutenant Governor or Chief commissioner.
Article 239 to 241 of the Indian Constitution in Part 8, deals with the formation of Union Territories. While there is LG (lieutenant Governor) in Delhi, Puducherry, Andaman and Nicobar islands, J&K and Ladakh , there is an Administrator in case of the rest UTs.
Union territories can have their own Legislative Assembly such as in the case of Delhi (1992), Puducherry (1963) and J&k but it doesn't mean that it will diminish the supreme control of the President and Parliament over them. We can say that the legislative Powers of Parliament in case of UTs are similar as with states. However, the legislative Assembly of UTs can also take important decisions on subjects written in the State and Concurrent list.
In case of failure of Constitutional machinery, the President has the power to appoint the Governor of a state as the administrator of an adjoining Union territory. In that capacity, the Governor is free to act independently of his council of Ministers.
The President can also take important decisions regarding the peace, progress and the good government of the Union Territory which doesn't have a Legislative Assembly. But for the UTs with assemblies, the President can legislate by making regulations only when the assembly is dissolved.
Under the 69th Constitutional amendment act of 1991, Delhi got its special status as Union Territory and the National capital of India and was provided with an administrative authority as Lieutenant Governor. It also resulted in the adoption of a legislative Assembly and a council of Ministers. Here the Chief minister is appointed by the President instead of Lt. Governor, while all other Ministers are appointed by the President on the advice of CM.
Now this 70 members legislative council can make laws on all the matters of State and concurrent list except the matters of Public order, Police and land.Delhi as a Union territory has a specific executive structure consisting of ; Lt. Governor, Chief Minister and Council of Ministers. It also has its separate High Court.
Here are the important Provisions regarding the status of Union Territories of India.
Here are some of the important Facts from the examination point of view.