In C++, the Standard Template Library (STL) provides a set of container classes that are designed to store and manipulate collections of elements efficiently. These containers are implemented using templates, which allows them to be used with any type of data. The STL containers can be broadly classified into three categories:

1. Sequence containers: These containers store elements in a linear sequence, such as a list or an array. The most commonly used sequence containers are:

• vector: This is a dynamic array that can grow or shrink in size as needed. It provides fast access to individual elements, and also supports efficient insertion and deletion of elements at the end.

• list: This is a doubly-linked list that provides efficient insertion and deletion of elements at any position. However, it does not provide fast random access to individual elements.

• deque: This is a double-ended queue that provides fast insertion and deletion of elements at both ends. It also provides fast random access to individual elements.

2. Associative containers: These containers store elements in a sorted order, and provide efficient lookup and insertion of elements based on their keys. The most commonly used associative containers are:

• set: This is a container that stores a sorted set of unique elements. It provides fast lookup and insertion of elements based on their values.

• map: This is a container that stores a sorted map of key-value pairs. It provides fast lookup and insertion of elements based on their keys.

• multiset and multimap: These are similar to set and map, but they allow duplicate elements to be stored.

3. Container adaptors: These are special containers that provide a specific interface to an underlying container. The most commonly used container adaptors are:

• stack: This provides a LIFO (last-in, first-out) interface to a sequence container.

• queue: This provides a FIFO (first-in, first-out) interface to a sequence container.

• priority_queue: This provides a priority queue interface to a sequence container, where elements are ordered based on a priority value.

STL containers provide a rich set of member functions and iterators that allow for efficient manipulation and traversal of the container elements. They also provide a standard and consistent interface that makes it easy to use different containers interchangeably in the same code.