https://www.fs.usda.gov/wildflowers/beauty/lichens/about.shtml
https://byjus.com/biology/classification-of-lichens/

Based on their growth

1. Crustose Lichens

Crustose lichens are flat, thin and without any distinct lobes. They are usually found closely attached to stones, rocks, barks and the trunk of trees. Haematomma puniceum and Graphic scripta are the best examples of crustose lichens.

1. Foliose Lichens

The foliose lichens are more attractive compared to other types of lichens. They are flat shaped, broad, smooth and leaf-like structures, which often resemble crinkled and twisted leaves. It holds a distinct upper and a lower surface. This type of lichens is generally found attached to rocks and twigs with the help of the rhizoid. Cetraria, Cluiudhuria, Parmelia and Xanthoria are a few examples of foliose lichens.

1. Fruticose Lichens

These are the most important types of lichens, which are thin and freely branched. The fruticose lichens constitute larger and attractive growths standing out from the branches of trees, foliage and rocks. Cladonia, Ramalina and Usnea are the common examples of fruticose lichens.

Based on their habitat:

Lignicolous. These types of lichens live in the woods.
Corticolous- These types of lichens live on the bark of trees.
Saxicolous- These types of lichens live on stones or rocks.
Marine. These types of lichens are found growing on the siliceous rocks, near the shores of the sea.
Freshwater. These types of lichens are found growing on the hard siliceous rocks, especially around the freshwater.
Terricolous- These types of lichens are found growing on the soil, therefore also called the terrestrial lichens.
Based on their internal structure:

Heteromerous lichens
Homoiomerous lichens.
Based on their fungal partner:

Ascolichens
Basidiolichens
Hymenolichens less ↑