What is ranked in OGS

i sometimes see ranked and unranked what is that

Ranked games influnce your rating. Depending on the result of such games your rank (your strength that is displayed as kyu or dan) will either grow or be lowered.

Unranked games do not influence your rating. You can think of them as “just for fun”, people sometimes use them to test unusual openingsbor stuff or if they just don’t feel like playingbwith the “pressure” right now