Scala is a feature-rich programming language that combines object-oriented and functional programming paradigms. Here are some of its main features:

1. Object-Oriented and Functional Programming : Scala seamlessly integrates both object-oriented and functional programming styles. It supports object-oriented programming features like classes, inheritance, and polymorphism, while also providing powerful functional programming constructs such as higher-order functions, immutability, and pattern matching.

2. Type Inference : Scala's strong type system is equipped with advanced type inference capabilities. The compiler can often infer the types of expressions and variables, reducing the need for explicit type annotations and making the code more concise and expressive.

3. Immutable Data Structures : Scala encourages the use of immutable data structures by default. Immutable data promotes thread-safety, facilitates reasoning about program behavior, and enables functional programming techniques. However, Scala also provides mutable data structures for situations that require mutable state.

4. Pattern Matching : Scala offers pattern matching, a powerful mechanism for deconstructing and matching the structure of data. It allows developers to write concise and expressive code for tasks like conditional branching, data extraction, and recursive algorithms.

5. Higher-Order Functions : Scala treats functions as first-class citizens, allowing them to be assigned to variables, passed as arguments, and returned as results. Higher-order functions enable functional composition, modularity, and the implementation of advanced functional programming patterns.

6. Concurrency and Parallelism : Scala provides built-in support for concurrent and parallel programming. It offers the Actor model through libraries like Akka, which simplifies the development of concurrent and distributed systems. Additionally, Scala's collections library provides parallel operations, enabling efficient parallel processing of data. 7. Interoperability with Java : Scala runs on the Java Virtual Machine (JVM) and can seamlessly interoperate with Java code. It can call Java libraries and use Java frameworks, which allows developers to leverage the vast ecosystem of existing Java tools and libraries.

8. DSL (Domain-Specific Language) Support : Scala's expressive syntax and advanced language features make it well-suited for creating domain-specific languages (DSLs). Developers can build DSLs that are concise, readable, and domain-specific, enabling domain experts to write code that closely resembles the problem domain.

9. Lazy Evaluation : In lazy evaluation or call-by-need, expressions are not evaluated until their first use, or until their demand. Computations are lazy in Scala by default. To declare a lazy variable, use the lazy keyword.

10. Case classes and Pattern matching : Case classes in Scala are immutable classes that can be decomposed via pattern matching. Case classes include public and immutable parameters by default. These classes support pattern matching, which makes it easier to write logical code.

11. Type Parameterization and Higher-Kinded Types : Scala supports type parameterization, allowing generic types and functions to work with different data types. It also introduces higher-kinded types, which provide advanced type abstraction capabilities and enable the creation of more generic and reusable code.

12. REPL (Read-Eval-Print Loop) : Scala comes with a powerful interactive shell called the REPL, which allows developers to experiment, test code snippets, and quickly prototype ideas. The REPL provides immediate feedback, making it an effective tool for learning, exploring, and debugging code.