English spelling is famous for being irregular, and the reputation is deserved. But it is not random. A small number of rules cover a large share of the words that cause trouble, and knowing which rules actually hold saves a writer from memorising lists they will forget.
The useful distinction is between rules that are reliable, rules that are tendencies, and rules that were invented by a schoolteacher in the nineteenth century and have been repeated ever since.
The rules that hold
I before E, except after C — when the sound is "ee." The full rule is usually taught without the qualifier, which is why people think it fails. Applied only to words where the vowel pair says "ee," it works: receive, deceive, ceiling, receipt. Applied to every word, it meets "their," "weird," "foreign," and "seize," which are not counterexamples so much as words the rule never covered.
The version worth remembering: when the sound is "ee" and the letter before is C, write EI. Otherwise, IE. Then memorise the handful of exceptions: seize, weird, protein, either, neither, forfeit.
Drop the E before a vowel suffix. Make becomes making. Hope becomes hoping. Large becomes largish (consonant suffix, E stays). The rule is reliable with a small set of exceptions: words ending in -ce and -ge keep the E before -able and -ous to preserve the soft sound — noticeable, manageable, courageous.
Double the final consonant before a vowel suffix when the stress is on the last syllable. Stop becomes stopped. Begin becomes beginning. Visit becomes visited, because the stress is on the first syllable. This rule is more reliable than most, once you can hear the stress.
Change Y to I before a suffix, unless the suffix starts with I. Happy becomes happiness. Carry becomes carried. But carry + ing becomes carrying, because the suffix already starts with I. Words ending in a vowel plus Y keep the Y: play becomes played.
Use -able for words formed from complete verbs, -ible for the rest. This is a tendency rather than a rule, but it covers most cases. If the word without the suffix is a complete English verb, -able is likely: readable, breakable, manageable. If it is not, -ible is likely: visible, possible, terrible.
The rules that are folklore
"I before E except after C" as an absolute. Already covered: the rule has a condition, and without it, it fails constantly.
"Never end a sentence with a preposition." Not a spelling rule, and not a rule at all. It was imported from Latin grammar in the seventeenth century and has been ignored by good writers ever since. "What are you looking at?" is correct English.
"A before E except after C" for -ance/-ence. The suffix choice depends on the root, not on the letter before it. "Attendance" and "existence" both follow C and take different endings.
"Two vowels together make a long sound." True often enough to be taught, false often enough to mislead. "Head," "bread," and "great" all break it in different directions.
"Sound it out." English spelling preserves the pronunciation of earlier centuries, which is why "knight" and "night" rhyme but do not look alike. Sounding out helps with some words and actively misleads with others.
The patterns worth memorising
Some spelling problems are better solved by memorising a pattern than by applying a rule.
-tion, -sion, -cian. The ending depends on the root. Words ending in -t or -te usually take -tion: act → action, create → creation. Words ending in -d, -de, or -se often take -sion: decide → decision, expand → expansion. Words for people and professions take -cian: musician, electrician, physician.
-ance vs -ence. There is no reliable rule, but there are families. Words from verbs ending in -ant usually take -ance: relevant → relevance. Words from adjectives ending in -ent usually take -ence: different → difference.
-ise vs -ize. Both are correct. British publishing has moved towards -ise; American publishing uses -ize. The important thing is consistency within a document. The British vs American spelling guide covers the wider differences.
Silent letters. Knock, knee, gnat, write, wrist, psalm, debt, doubt. The letters were pronounced when the spelling was fixed and are not pronounced now. Memorise the groups; there is no pattern to derive.
The words that catch everyone
A few words are misspelled so often that the misspelling has become a landmark. The 50 most commonly misspelled words list covers them in detail. The short version:
- accommodate (two C, two M)
- separate (there is "a rat" in the middle)
- definitely (no A in the middle)
- occurrence (two C, two R)
- necessary (one C, two S)
- embarrass (two R, two S)
- recommend (one C, two M)
- receipt (EI after C, silent P)
Mnemonics help more than rules for these. "There is a rat in separate" is silly and it works.
A practical approach
Do not try to learn all of English spelling. Learn the four rules that hold, memorise the twenty words you personally get wrong, and keep a list of the errors a spellcheck misses.
Most writers have a stable set of about fifteen recurring mistakes. Finding them and fixing them once removes them from every future draft. That is a better use of an afternoon than reading a list of five hundred rules you will not remember.
Spelling is a surface skill. It matters because errors distract, not because they are interesting. Get the recurring ones right, run a checker, and spend the saved attention on the sentence.