-(i)bdi

Use -(i)bdi when you did not watch the event yourself. You see only its result, such as snow on the ground, or someone tells you about it. English often adds words like "I see", "it turns out" or "apparently" to say the same thing.

1. Building the form
Take the verb stem, add -ib after a consonant or -b after a vowel, then the person ending:

• kel- + -ib + -man → kelibman (I have come, it turns out)
• kel- + -ib + -san → kelibsan (you have come, familiar)
• kel- + -ib + -di → kelibdi (he or she has come, it seems)
• kel- + -ib + -miz → kelibmiz (we have come, it turns out)
• kel- + -ib + -siz → kelibsiz (you have come, polite)

After a vowel: oʻqi- + -b + -di → oʻqibdi, ishla- + -b + -di → ishlabdi. For ular, say kelibdi or kelibdilar.
These are the long endings of the present tense. The simple past -di uses the short ones, so it is keldim but kelibman.

2. When to use it

• You see the result: you open the curtains and the street is white: Qor yogʻibdi! (It has snowed!)
• Someone told you: Anvar Toshkentga ketibdi (Anvar has gone to Tashkent, I hear).
• It happened to you without your noticing: Uxlab qolibman (I overslept), Kalitni uyda qoldiribman (I left the key at home, I realize).
• Fairy tales: nobody alive saw the events, so stories are told this way: Chol oʻrmonga boribdi (The old man went to the forest).

3. Negative and question

• Negative: put -ma- after the stem, then -b: kel- + -ma- + -b + -di → kelmabdi (he hasn't come, it seems).
• Question: add -mi at the end: Kelibdimi? (Has he come?)

4. Four verbs describe the present
With turmoq, oʻtirmoq, yotmoq and yurmoq, the -ib form usually describes what is going on right now, with no sense of discovery: U doʻstini kutib turibdi (He is waiting for his friend), Bola kitob oʻqib oʻtiribdi (The child is sitting reading a book).

5. Spelling
In speech -ibdi often sounds like -ipti (kelipti), but it is always written -ibdi: ketibdi, kelmabdi.

6. -ibdi or ekan?
Ekan also marks something you just found out: U kelgan ekan (So he had come). -ibdi does it inside one verb, while ekan can also follow nouns: U shifokor ekan (So he is a doctor).