Many people have the custom to visit the graves of their parents before Rosh Hashanah.
The origin of this practice is in Talmud (Ta'anit, 16a), which teaches that on communal fast days of repentance and reflection,people used to go and pray in cemeteries.
The Talmud offers two reason for this; one is to remind us of our mortality, while the other is to ask that our righteous departed ancestors intercede on our behalf.
The Talmud makes a distinction between these two reasons by considering the practical instance of going to a non-Jewish cemetery, which recalls mortality, though not our ancestors.