1. Electrolysis of Water: This is a clean method that uses electricity to split water molecules into hydrogen and oxygen. The process is described by the following equation:

```

2H₂O(l) → 2H₂(g) + O₂(g)

```

2. Steam Reforming of Natural Gas: This is the most common industrial method for producing hydrogen. Natural gas (primarily methane) reacts with steam at high temperatures and in the presence of a catalyst, producing hydrogen and carbon dioxide.

```

CH₄(g) + H₂O(g) → CO(g) + 3H₂(g)

```

3. Reaction of Active Metals with Acids: Hydrogen can be produced by reacting certain metals (like zinc or magnesium) with dilute acids (like hydrochloric acid or sulfuric acid). This is a simple laboratory method for generating small amounts of hydrogen.

```

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

```

These are just a few examples, and there are many other ways to prepare hydrogen. The specific method used depends on the desired purity, quantity, and cost considerations.