I before E except after C
"I before E, except after C" is a mnemonic rule of thumb for English spelling. If one is unsure whether a word is spelled with the digraph ⟨ei⟩ or ⟨ie⟩, the rhyme suggests that the correct order is ⟨ie⟩ unless the preceding letter is ⟨c⟩, in which case it may be ⟨ei⟩.
Source: Wikipedia — I before E except after C (CC BY-SA 4.0)