Ferns share these features:
The green photosynthetic part of the plant (leaf) is called a Frond.
New fronds uncurl by unrolling from an initial tight coil.
They reproduce by producing spores, inside sori, formed on the lower surface of the pinnae of the frond.
Fibrous roots originate from the rhizomes.
Ferns have both a sporophyte and gametophyte generation.
This link illustrates the alternation between sporophyte and gametophyte generations: