A **Redis Set** is a data structure that is available in Redis and is essentially a collection of strings with the below properties:
1) each string is unique and occurs only once in a Set
2) the strings are unordered and Redis can return the elements in any order at every call

Conceptually, it is similar to the **HashSet** functionality available in Java or C#.

# Create a Redis Set 

Let's create a Redis set named **Months** using the **SADD** command and store the name of the first four months to it:

```
> SADD Months January February March April
(integer) 4
```
# View members
Set members can be viewed using the **SMEMBERS** command:
```
> SMEMBERS Months
1) "April"
2) "March"
3) "February"
4) "January"
```





# Remove a member
To remove a member from the set, we can use the **SREM** command:
```
> SREM Months April
1
> SMEMBERS Months
1) "March"
2) "February"
3) "January"
```
# Check membership
The **SISMEMBER** command can be used to check the membership in the set. Here, *January* exists in the set, but *December* does not:
```
> SISMEMBER Months January
(integer) 1
> SISMEMBER Months December
(integer) 0
```

# More on Redis Set

A Redis Set is a very efficient data structure: operations like adding a member, deleting a member, or checking if a member exists in the Set can be done in constant time or O(1).

Apart from these basic operations, Sets offer very powerful operations like #key# unions: SUNION #key#, #key# intersections: SINTER #key#, #key# difference: SDIFF #key#, #key# extracting a random element: SPOP #key#, etc. 

Redis Sets allow the storage of a maximum of `$2^{32} - 1$`(more than 4 billion) members per set.

Redis Sets are used to solve various use cases, like counting unique visitors using IP addresses, session caching, and analyzing customer behavior in online stores (to name a few).



# Remove a member
To remove a member from the set, we can use the **SREM** command:
```
> SREM Months April
1
> SMEMBERS Months
1) "March"
2) "February"
3) "January"
```
# Check membership
The **SISMEMBER** command can be used to check the membership in the set. Here, *January* exists in the set, but *December* does not:
```
> SISMEMBER Months January
(integer) 1
> SISMEMBER Months December
(integer) 0
```

# More on Redis Set

A Redis Set is a very efficient data structure: operations like adding a member, deleting a member, or checking if a member exists in the Set can be done in constant time or O(1).

Apart from these basic operations, Sets offer very powerful operations like #key# unions: SUNION #key#, #key# intersections: SINTER #key#, #key# difference: SDIFF #key#, #key# extracting a random element: SPOP #key#, etc. 

Redis Sets allow the storage of a maximum of `＄2^{32} - 1＄`(more than 4 billion) members per set.

Redis Sets are used to solve various use cases, like counting unique visitors using IP addresses, session caching, and analyzing customer behavior in online stores (to name a few).



What are sets in Redis?

Redis Sets are unordered collections of unique strings, allowing efficient operations like membership checks, adding, and removing members in O(1) time.