### What is MD5?

The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value.

From [Wikipedia MD5](https://en.wikipedia.org/wiki/MD5)

You can simply think that there is a function called md5(), by providing a string to that function and it will return a MD5 string to you. A MD5 string is fixed length. That means whatever how much data you input to the md5() function. The string length of output will always the same.

### How to generate MD5 string?

Different programming language has their own methods / library to generate a MD5 string. 

In NodeJS, a built in module called `crypto` can help you do the staff :

```js
// import module
const crypto = require('crypto');

// input data
var data = 'hello world';

// and md5 string of 'hello world'
var md5String = crypto.createHash('md5').update(data).digest('hex');
```

There are many other digest methods that supported by `crypto` module. You can navigate to Tools page to try out the online MD5 converter.