Мы долго искали ключ и всё-таки нашли его.

and

Breakdown of Мы долго искали ключ и всё-таки нашли его.

• мы: we
• найти: to find
• ключ: the key

Questions & Answers about Мы долго искали ключ и всё-таки нашли его.

Why is it искали in the first part but нашли in the second?

This is a classic Russian aspect contrast.

• искали is from искать (imperfective): it describes an ongoing process — they were searching, looking for some time.
• нашли is from найти (perfective): it shows a completed result — they ended up finding it.

So Russian naturally uses:

• imperfective for the activity/process
• perfective for the successful result

That is why Мы долго искали... sounds right for we searched for a long time, and ...нашли его sounds right for found it.

Why do we use долго with искали?

Долго means for a long time. It fits very naturally with an imperfective verb, because imperfective verbs describe duration, repetition, or process.

So:

• долго искали = they were searching for a long time

With a perfective verb, долго is usually less natural if you want to emphasize the whole process of searching. The searching itself is ongoing, so искали is the expected choice.

What exactly does всё-таки mean here?