is a query language that allows developers to query data from different data sources, such as databases, collections, or XML documents. It is integrated into C# and provides a unified syntax for querying different types of data.

LINQ queries are similar to SQL queries, but they are written in a C# syntax with a fluent API. LINQ queries can be used to filter, sort, group, join, and transform data. LINQ queries can be executed immediately or deferred, meaning they can be executed when the query results are actually needed.

LINQ supports querying different types of data sources, including:

– LINQ to Objects: querying collections of objects in memory.
– LINQ to SQL: querying relational databases using SQL.
– LINQ to XML: querying XML documents using XPath or XQuery.
– LINQ to Entities: querying relational databases using the Entity Framework.

LINQ provides a rich set of query operators, such as Where, Select, OrderBy, GroupBy, Join, and Aggregate, that can be used to compose complex queries. LINQ also supports lambda expressions and anonymous types, making query expressions more concise and expressive.

Here is an example of a LINQ query that retrieves all the customers from a list of objects:

var customers = from customer in customerList
where customer.City == “New York”
orderby customer.LastName descending
select customer;

In this query, `customerList` is a collection of objects with properties like `City` and `LastName`. The query filters the customers based on the city, sorts them by last name in descending order, and selects the customers that match the criteria.

LINQ is a powerful tool for querying and manipulating data in a concise and expressive way. It simplifies the process of writing complex queries and reduces the amount of boilerplate code that is typically involved in querying data.