Life is full of choices, and choices need comparison. Which apartment is cheaper? Which route is faster? Who is the best cook in your family? When you shop, travel, or plan anything with other people, you constantly compare two things or pick the top one from a group. Comparatives ('cheaper', 'more comfortable') and superlatives ('the cheapest', 'the most comfortable') are the tools for exactly this.

If you get the forms wrong — 'more warmer', 'the most cheapest', 'gooder' — people usually still understand, but the mistake is loud and easy to hear. The good news: the system is small and regular. Learn one short-word rule, one long-word rule, and three irregular words, and you can compare almost anything in English.

First, the two jobs. A COMPARATIVE compares two things and usually appears with 'than': 'This room is warmer than that one.' A SUPERLATIVE picks the extreme from three or more things and takes 'the': 'It is the warmest room in the house.' So: two things, -er + than; a whole group, the + -est.

How you build the form depends on the length of the adjective. Short adjectives (one syllable) add -er and -est: cold, colder, coldest; cheap, cheaper, cheapest. Small spelling notes: if the word ends in -e, just add -r or -st (nice, nicer, nicest); if it ends in one vowel plus one consonant, double the consonant (big, bigger, biggest; hot, hotter, hottest).

Long adjectives (three or more syllables) do not change. Instead, put 'more' or 'the most' in front: expensive, more expensive, the most expensive; comfortable, more comfortable, the most comfortable. Two-syllable adjectives are mixed, but here is a safe guide: if the word ends in -y, change -y to -ier or -iest (happy, happier, happiest; easy, easier, easiest); for most other two-syllable words, 'more' and 'most' are a safe choice (more famous, more careful).

The most important rule of all: choose ONE method, never both. The -er ending and 'more' do the same job, so combining them is wrong. 'More warmer' says 'warmer' twice. Say 'warmer' or, with a long word, 'more comfortable' — never 'more warmer' or 'most cheapest'. Also memorize the three big irregulars: good, better, the best; bad, worse, the worst; far, farther, the farthest. There is no 'gooder' or 'badder'.

Two extras that make you sound natural. To say two things are equal, use as + adjective + as: 'My bag is as heavy as yours.' To compare downward, use 'less' or 'not as ... as': 'The bus is less expensive than the train', or, more common in speech, 'The bus is not as expensive as the train.'

1. 1. My new phone is faster than my old one.

   One-syllable adjective: add -er and follow with 'than'.

2. 2. Today is hotter than yesterday.

   'Hot' doubles its final consonant before -er: hotter, not hoter.

3. 3. This is the cheapest hotel in the city.

   A superlative takes 'the' and points to one extreme in a group.

4. 4. The train is more expensive than the bus.

   A long adjective uses 'more', with no -er ending.

5. 5. She is the most careful driver in our family.

   Superlative of a longer adjective: the most + adjective.

6. 6. Is your new job better than the old one?

   'Good' is irregular: better, never gooder or more good.

7. 7. The traffic is worse on Friday evenings.

   'Bad' is irregular too: worse, and the superlative is the worst.

8. 8. Winter days are shorter than summer days.

   Plural subjects work the same: adjective + -er + than.

9. 9. This exercise is easier than the last one.

   Two-syllable adjective ending in -y: change -y to -ier.

10. 10. That was the happiest day of my life.

    -y becomes -iest in the superlative: happiest.

11. 11. Which is the largest room in the apartment?

    Questions use the same superlative form with 'the'.

12. 12. My suitcase is as heavy as yours.

    Use as + adjective + as to say two things are equal.

13. 13. The bus is not as fast as the metro.

    'Not as ... as' is a natural way to compare downward.

14. 14. Online tickets are less expensive than tickets at the door.

    'Less' is the opposite of 'more' with long adjectives.

15. 15. Her cold is getting worse, so she should rest.

    Comparatives can show change over time with 'get'.

Mistake one: doubling the comparison, as in 'This room is more warmer.' The -er ending already means 'more', so adding 'more' repeats it. Use one method only: 'warmer' for short adjectives, 'more comfortable' for long ones. The same applies to superlatives: 'the most cheapest' is wrong; say 'the cheapest'.

Mistake two: forgetting 'than' or replacing it, as in 'My city is bigger that yours' or 'bigger from yours.' The comparison word in English is 'than' and only 'than': 'bigger than yours.' Also, superlatives need 'the': say 'the best coffee in town', not just 'best coffee in town' when you mean the number one.

Mistake three: forcing regular endings onto irregular words — 'gooder', 'baddest', 'more good'. The irregulars must simply be memorized: good, better, best; bad, worse, worst; far, farther, farthest. They are among the most frequent words in daily comparison, so drilling these three families pays off fast.

• Short adjective: add -er / -est. Long adjective: use more / the most.
• Never combine them: warmer OR more warm-type words, never 'more warmer'.
• Comparing two things? Use -er + THAN. Picking the top one? Use THE + -est.
• Memorize: good, better, best; bad, worse, worst; far, farther, farthest.
• Adjectives ending in -y: happy becomes happier, happiest.
• Equal things: as ... as. Downward: not as ... as, or less + adjective.