> For the complete documentation index, see [llms.txt](https://gchandra.gitbook.io/big-data-and-tools-with-nosql/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gchandra.gitbook.io/big-data-and-tools-with-nosql/nosql/redis/data-structures/list.md).
# List
Redis lists are linked lists of string values. Redis lists are frequently used to:
* Implement stacks and queues.
* Build queue management for background worker systems.
* [`LPUSH`](https://redis.io/commands/lpush) adds a new element to the head of a list; [`RPUSH`](https://redis.io/commands/rpush) adds to the tail.
* [`LPOP`](https://redis.io/commands/lpop) removes and returns an element from the head of a list; [`RPOP`](https://redis.io/commands/rpop) does the same but from the tails of a list.
* [`LLEN`](https://redis.io/commands/llen) Returns the length of a list.
* [`LMOVE`](https://redis.io/commands/lmove) Atomically moves elements from one list to another.
* [`LTRIM`](https://redis.io/commands/ltrim) Reduces a list to the specified range of elements.
Image website tracking user experience
**LPUSH** (add elements to the beginning of a list):
* **Example**: `LPUSH "recentPages" "/home"`
* `LPUSH "recentPages" "/about" "/contact"`
* **Use case**: Track a user's page visit history. New pages the user visits are added to the front, showing the most recent visit at the top.
The list will look like
```
contact about home
```
**RPUSH** (add elements to the end of a list):
* **Example**: `RPUSH "pageQueue" "/checkout" "/confirmation" "/thankyou"`
* **Use case**: Queue pages for batch processing, like sequentially processing user actions.
**LRANGE** (get a range of elements from a list):
* **Example**: `LRANGE "recentPages" 0 -1`
* **Use case**: Display the pages a user has recently visited on their profile or dashboard.
**LLEN** (get the length of a list):
* **Example**: `LLEN "recentPages"`
* **Use case**: Show the number of pages users have visited in their current session or a set period.
**LPOP** (remove and get the first element in a list):
* **Example**: `LPOP "recentPages"`
* **Use case**: Remove the oldest page in the user's visit history when the list exceeds a certain size to maintain only a fixed number of recent pages.
**RPOP** (remove and get the last element in a list):
* **Example**: `RPOP "pageQueue"`
* **Use case**: Process the last action in a user's action queue, like the previous step in a multi-step form.
How do we track which User accessed which page?
Remember Namespaces?
* `LPUSH "user:123:recentPages" "/home"`
* `LPUSH "user:123:recentPages" "/contact"`
* `LRANGE "user:123:recentPages" 0 -1`
### Use Case: Managing Queues of Work
**FIFO**: First In, First Out
**LIFO**: Last In, First Out
**Create a Task Queue**
```
RPUSH taskQueue "task1" "task2" "task3"
LRANGE taskQueue 0 -1
```
**Worker Fetching a Task (FIFO):**
```
LPOP taskQueue
```
```
LRANGE taskQueue 0 -1
```
**Creating a Stack or LIFO Queue:**
```
LPUSH jobStack "task1" "task2" "task3"
```
```
LPOP jobStack
```
