A linked list is a data structure that consists of a sequence of elements, each of which contains a reference (or “link”) to the next element in the sequence.

Each element in a linked list is typically called a “node”. The first node in the list is called the “head”, and the last node is the “tail”.

Linked lists can be either singly-linked, where each node only contains a reference to the next node, or doubly-linked, where each node contains a reference to both the next and previous nodes.

Linked lists have several advantages over arrays, including dynamic sizing, efficient insertion and deletion of elements, and the ability to easily implement certain algorithms such as sorting and reversing.

**Singly Linked List**

A singly linked list is a type of linked list data structure where each node has a pointer pointing to the next node in the list. The first node of a singly linked list is called the head, and the last node is called the tail.

Each node in a singly linked list typically contains a data element and the pointer to the next node. This structure is used to implement a linear sequence of elements, where each element is connected to its next element, but not to its previous element.

The singly linked list is a basic data structure and is used in many algorithms and data manipulation operations.

It’s easy to implement and efficient at inserting or deleting elements at the beginning of the list, but not efficient when it comes to insertion or deletion at the end of the list as it requires traversing the whole list.

**1. Structure of Singly Linked List**

A singly linked list is a data structure that consists of a sequence of elements, where each element, called a node, contains a reference to the next element in the list.

The first node in the list is the head and the last node is the tail. They are commonly used in applications where a list of items needs to be processed in a specific order.

For instance, it can be used to store a list of tasks that need to be completed, with the head node being the first task and the tail node being the last task.

Also, singly linked lists are often utilized in algorithms that need to process a list in reverse order, for example, the quicksort sorting algorithm uses a singly linked list to store the list of items that needs to be sorted and by processing the list in reverse order, it can sort the list more efficiently.

**2. Creation and Traversal of Singly Linked List **

A linked list is a data structure that stores a sequence of elements, called nodes. Each node has a reference to the next node in the list. The first node in the list is the head and the last node is the tail.

To create a singly linked list, we first need to create a node class that has two data members: an integer value and a reference to the next node in the list.

Then, we create a Linked List class that has two data members: a head node and a tail node. The head node stores the first element in the list, and the tail node stores the last element.

To add an element to the list, we create a new node, set the next reference of the previous tail node to point to the new node and set the new node as the new tail.

To remove an element, we find the node that contains the value we want to remove by traversing the list, set the next reference of the previous node to point to the next node.

To search for an element, we traverse the list until we find the node with the matching value. To traverse the list, we start at the head node and follow the next references until we reach the tail node.

**Doubly Linked List**

A doubly linked list is a type of linked list data structure where each node has two pointers, one pointing to the next node in the list and another pointing to the previous node.

This allows for easy traversal of the list in both directions, from head to tail and tail to head. The first node of a doubly linked list is called the head, and the last node is called the tail.

Each node in a doubly linked list typically contains a data element and the two pointers, one to the previous node and one to the next node.

This structure provides more flexibility compared to a singly linked list and can be useful in certain algorithms and data manipulation operations.

**1. Structure of Doubly Linked List**

A doubly linked list is a type of linked list data structure where each node has a pointer pointing to both the next and previous nodes in the list.

The first node of a doubly linked list is called the head, and the last node is called the tail. Each node in a doubly linked list typically contains a data element and the pointers to the next and previous nodes.

This structure is used to implement a linear sequence of elements, where each element is connected to its next and previous element.

The doubly linked list is a more complex data structure than the singly linked list and is used in many algorithms and data manipulation operations.

It is efficient at inserting or deleting elements at both the beginning and end of the list, unlike singly linked list.

**2. Creation and Traversal of Doubly Linked List **

A doubly linked list is a data structure that stores a sequence of elements, like a singly linked list, but with the added feature of having a reference to the previous element as well as the next element.

This allows for fast insertion and deletion of elements, as well as the ability to traverse the list forwards and backwards. To create a doubly linked list, a Node class needs to be created with data and next attributes, as well as a previous attribute.

Then a class representing the list is created with head and tail attributes. To add data to the list, a new node is created and the previous and next references are set.

To traverse the list, a current node variable is used to keep track of the position, and a while loop continues until the current node is None, at which point the end of the list is reached.

Within the loop, the data of the current node is printed and the current node is set to the next node before continuing.

**Circular Linked List**

A circular linked list is a type of linked list data structure where the last node in the list points back to the first node, creating a loop or a circular structure.

This means that the last node in the list has a reference to the head node, and the head node has a reference to the last node, creating a continuous cycle.

This type of linked list is useful for situations where it is necessary to traverse a list in a circular fashion, such as in a circular buffer or a cyclic data structure.

Additionally, it allows for quick insertion and deletion of elements at the front and rear of the list.

**1. Circular Linked List Structure**

A circular linked list is a type of data structure that uses linked list technology to store data in a linear, sequential fashion. It has no beginning or end – it is essentially a ring of nodes.

This makes circular linked lists ideal for applications where data needs to be processed in a continuous loop, such as in real-time applications or simulations.

It’s typically implemented using a singly linked list data structure and uses a “head” pointer that points to the first node. It’s efficient for memory usage, easy to implement and can add/remove data at any time, making it ideal for real-time applications.