We use -Dİr to make generalizations and predictions. In this first part you will learn about its generalization usage.
In Turkish we use -Dİr in adages and proverbs.
Çalışmak ibadetin yarısıdır.
To work is half of worship.
Başlamak bitirmenin yarısıdır.
Well begun is half done. [Lit.] To start is half of finishing.
It is also used in formal accounts, storytelling or addressing large crowds. For example:
Atatürk 1881'de doğmuştur.
Atatürk was born in 1881.
Mutlaka bu millet aydınlınacaktır.
Surely this nation will be enlightened.
These sentences would be grammatically acceptable without the -Dİr, but adding it reinforces the meaning.
It conveys either that these things are generally known or these things surely happened, or will happen. That is why it is not redundant to add -Dİr.
-Dİr is added to verbs after their tense endings -mİş, -EcEk, -(İ)yor, -mElİ, or -mEktE(which you will learn about later).
It can also be added to nouns.