die Erinnerung
memory
An image, a feeling, or information from the past that is stored in the mind.
Ich habe viele schöne Erinnerungen an meine Kindheit.
I have many beautiful memories of my childhood.

memory / reminder
Loading your saved state.
memory
An image, a feeling, or information from the past that is stored in the mind.
Ich habe viele schöne Erinnerungen an meine Kindheit.
I have many beautiful memories of my childhood.

The noun 'die Erinnerung' is derived directly from the verb 'sich erinnern' (to remember). The ending '-ung' is a typical way for German verbs to become feminine nouns.
Wenn du dich an etwas erinnerst, hast du eine Erinnerung daran.
When you remember something, you have a memory of it.
'Erinnerung' is almost always used with the preposition 'an' and the accusative. The structure is: 'die Erinnerung an jemanden/etwas' (the memory/reminder of someone/something).
Die Erinnerung an den letzten Sommerurlaub macht mich glücklich.
The memory of the last summer vacation makes me happy.
When referring to images stored in memory, 'Erinnerung' is often combined with verbs like 'wecken' (to awaken), 'wachrufen' (to call up), or 'haben' (to have). A very typical expression is also 'in Erinnerungen schwelgen' (to indulge in memories / to reminisce).
Alte Lieder können starke Erinnerungen wecken.
Old songs can awaken strong memories.
In an official or business context, 'Erinnerung' usually means 'Mahnung' (reminder notice/payment reminder). Signal words are verbs like 'schicken' (to send), 'bekommen' (to get), or 'erhalten' (to receive), often in connection with invoices or deadlines.
Ich habe eine Erinnerung erhalten, meine Bibliotheksbücher zurückzugeben.
I received a reminder to return my library books.
When 'Erinnerung' describes an object, the preposition 'als' is often used. The typical structure is 'etwas als Erinnerung an etwas behalten' (to keep something as a keepsake of something) or 'mitnehmen' (to take along).
Sie hat eine Postkarte als Erinnerung an ihre Reise nach Paris aufgehoben.
She kept a postcard as a keepsake of her trip to Paris.
hint / notice
'die Erinnerung' and 'der Hinweis' can both draw someone's attention to something. An 'Erinnerung' usually says: do not forget something, or still do it. It often refers to an appointment, a task, or an obligation. A 'Hinweis' gives information or a tip, or draws attention to a rule, danger, or possibility. Learners may confuse the words because both can appear as messages. In practical terms: an 'Erinnerung' helps against forgetting; a 'Hinweis' helps with understanding or paying attention to something.

Mein Handy schickt mir eine Erinnerung, damit ich den Arzttermin nicht vergesse.
My phone sends me a reminder so that I don't forget the doctor's appointment.
Am Eingang steht ein Hinweis, dass die Tür ab 18 Uhr geschlossen bleibt.
There is a notice at the entrance saying that the door remains closed from 6 p.m. onward.