What useful features and capabilities were added in…

Generic Lambda Captures: Allows capturing variables by value or reference with automatic type deduction.
```
// C++14
auto lambda = [x = get_value()] { return x; };
```
Return Type Deduction for Normal Functions: The compiler can determine the return type of a function if it can be deduced from return.
```
// C++14
auto func() {
    return 42; // return type is int
}
```
Binary Literals: Allows writing numbers in binary notation using prefixes 0b or 0B.
```
// C++14
int binary_value = 0b1101; // 13
```
Digit Separators in Numeric Literals: Allows using apostrophe ' for visual separation of digits in numeric literals.
```
// C++14
long big_number = 1'000'000;
```
decltype(auto): The behavior of decltype applies to automatic type deduction. Preserves reference and const, volatile qualifiers.
```
// C++14
int x = 5;
int& ref = x;
decltype(auto) result = ref; // result has type int&
```

Extended constexpr capabilities:

// C++14
constexpr int factorial(int n) {
    int res = 1;
    for (int i = 1; i <= n; ++i) {
        res *= i;
    }
    return res;
}

Guaranteed Copy Elision (Partial): Partially guarantees elimination of unnecessary copying in certain cases (e.g., returning rvalue from a function). Fully guaranteed in C++17.
Attributes: New standard attributes added:
- [[deprecated]]: Indicates an outdated element, issuing a warning when used.
- [[carries_dependency]]: Used in multithreaded programming for optimization.
std::make_unique: Convenient way to create objects managed by std::unique_ptr. Prevents some potential issues (e.g., memory leaks in case of exceptions).
```
// C++14
auto ptr = std::make_unique<int>(10);
```
std::shared_timed_mutex: Added for implementing read/write locks.
Small improvements in the standard library: Added std::integer_sequence, std::exchange, std::quoted, std::get for tuples by type.

What useful features and capabilities were added in C++14?