Standard ML (SML) is a functional programming language that was first introduced in the late 1980s. SML is based on the ML programming language, which was developed by Robin Milner at the University of Edinburgh in the 1970s. SML is known for its strong typing and powerful pattern matching features, which make it a popular choice for programming in areas such as compiler design, artificial intelligence, and theorem proving. In this guide, we will introduce you to the history of SML, explain its syntax, provide examples of how to write SML code, and explore some of its best applications.

History:
Standard ML was developed in the late 1980s by a group of researchers from universities in the UK and the US. The language was designed to provide a high-level, efficient, and type-safe programming environment that would be suitable for a wide range of applications. The first version of SML was published in 1990, and it has since gone through several revisions. The latest version of SML is called SML '97, which was standardized by the International Organization for Standardization (ISO).

Syntax:
SML is a statically typed language, which means that types are determined at compile-time rather than runtime. SML has a strict type system, which means that every expression in the language must have a well-defined type. SML supports several types, including integers, floating-point numbers, characters, strings, and lists. SML also supports several built-in operators and functions, such as arithmetic operators, comparison operators, and logical operators.

Example:
Here is an example of a simple SML program that prints the first ten Fibonacci numbers:

```
fun fib 0 = 0
  | fib 1 = 1
  | fib n = fib (n-1) + fib (n-2)

fun main () =
  let
    val n = 10
    val fibs = map fib (List.tabulate(n+1, fn i => i))
  in
    List.app print (List.take(fibs, n))
  end

```

This program defines a function `fib` that calculates the nth Fibonacci number, and a function `main` that prints the first n Fibonacci numbers using the `print` function. The `tabulate` function generates a list of integers from 0 to n, and the `map` function applies the `fib` function to each element of the list.

Applications:
SML is used in a variety of applications, including:

1. Compiler design: SML is often used to implement compilers for other programming languages due to its strong typing and pattern matching features.

2. Artificial intelligence: SML is used in the development of artificial intelligence systems, including natural language processing and machine learning.

3. Theorem proving: SML is used in the development of theorem provers, which are software tools that automatically prove mathematical theorems.

Conclusion:
Standard ML is a powerful functional programming language that is widely used in a variety of applications. In this guide, we have introduced you to the history of SML, explained its syntax, provided examples of how to write SML code, and explored some of its best applications. Whether you are a beginner or an experienced programmer, we hope that this guide has given you a good introduction to the world of SML programming.