When would you use a linked list vs. a vector?

Vector :

• Vector is another name for dynamic arrays. 
• It is the name used for the dynamic array data structure in C++. 
• If you have experience in Java you may know them with the name ArrayList. 
• (Java also has an old collection class called Vector that is not used nowadays because of problems in how it was designed.)
• Vectors are good for random read access and insertion and deletion in the back (takes amortized constant time).
• But bad for insertions and deletions in the front or any other position (linear time, as items have to be moved). 
• Vectors are usually laid out contiguously in memory, so traversing one is efficient because the CPU memory cache gets used effectively.

Linked lists :

• Linked lists, on the other hand, are good for inserting and deleting items in the front or back (constant time).
• But not particularly good for much else.
• For example deleting an item at an arbitrary index in the middle of the list takes linear time because you must first find the node. 
• On the other hand, once you have found a particular node you can delete it or insert a new item after it in constant time, something you cannot do with a vector. 
• Linked lists are also very simple to implement, which makes them a popular data structure.