Gawk, also known as GNU Awk, is a powerful programming language used for text processing and pattern matching. It is an extension of the original awk language, which was developed in the 1970s. Gawk is an open-source software and is available for free on multiple platforms including Linux, Windows, and macOS. It offers a range of features, including regular expressions, arrays, functions, and input/output operations, making it a popular choice for manipulating text data. In this guide, we will introduce you to Gawk programming language and help you get started with it.

Syntax:
Gawk programs are written in plain text files with a .awk extension. The basic structure of a Gawk program consists of a series of patterns and actions. A pattern is a regular expression that matches a specific pattern in the input data, and an action is a set of commands that are executed when a pattern is matched.

Here is an example of a simple Gawk program that prints out the lines of a file that contain the word "hello":

```
/Hello/ { print }
```

In this program, `/Hello/` is the pattern that matches any line containing the word "hello". The action `{ print }` is executed when a pattern is matched and it prints out the matched line to the output.

To run this program, save it to a file named "hello.awk", and run the following command in the terminal:

```
gawk -f hello.awk input.txt
```

In this command, "input.txt" is the input file that you want to process.

Applications:
Gawk is commonly used for text processing tasks, such as searching, filtering, and manipulating text data. It is often used in the following applications:

1. Data processing: Gawk can be used to extract and manipulate data from large data sets, such as log files and CSV files.

2. System administration: Gawk can be used to automate system administration tasks, such as parsing configuration files and monitoring system logs.

3. Text processing: Gawk can be used to manipulate text data, such as converting text to HTML, XML, or other formats.

4. Bioinformatics: Gawk can be used in bioinformatics to process DNA and protein sequences, and to analyze gene expression data.

Conclusion:
In this guide, we have introduced you to the Gawk programming language and provided you with an example program to get started. We have also discussed some of the common applications of Gawk, including data processing, system administration, text processing, and bioinformatics. Gawk is a powerful and versatile language that can help you automate tasks and manipulate text data efficiently. We encourage you to explore Gawk further and discover its many features and applications.