Peat is the earliest stage in the formation of coal.

Here's how it works:

1. Plant Matter: Peat forms from the accumulation of partially decayed plant matter, typically in waterlogged environments like bogs and swamps.

2. Peat Formation: Over time, the plant matter is compressed and compacted, forming peat.

3. Coal Formation: With further burial, heat, and pressure, peat is transformed into different types of coal, starting with lignite and progressing to bituminous and anthracite.

So, peat is the first step in a long process that ultimately leads to the formation of coal, a valuable fossil fuel.