Called and bought can both describe something that happened in the past, but the verbs were formed differently. Call becomes called by following the regular -ed pattern. Buy changes to bought, so it is irregular.
That basic difference between regular and irregular verbs affects both the simple past form and the past participle. Some verbs follow a predictable pattern, while others change in ways that need to be recognized as separate forms.
Regular and Irregular Verbs at a Glance
The difference is easiest to see by comparing the base form, past form, and past participle.
| Base Verb | Past Form | Past Participle | Type |
|---|---|---|---|
| repair | repaired | repaired | Regular |
| invite | invited | invited | Regular |
| hurry | hurried | hurried | Regular |
| slip | slipped | slipped | Regular |
| catch | caught | caught | Irregular |
| drive | drove | driven | Irregular |
| send | sent | sent | Irregular |
| throw | threw | thrown | Irregular |
A regular verb forms its past and past participle with the regular -ed ending, although the spelling may change slightly.
An irregular verb has a past form, past participle, or both that do not follow that regular pattern.
What Makes a Verb Regular?
Regular verbs use the standard -ed pattern for both the simple past and past participle.
For example:
polish → polished → polished
wait → waited → waited
explain → explained → explained
Compare the forms in sentences:
Nina polished the wooden table yesterday.
She has polished the chairs as well.
The same form, polished, works as both the simple past and the past participle.
That predictable pattern is what makes polish a regular verb.
Regular Does Not Mean the Spelling Never Changes
Some regular verbs need a spelling adjustment when the -ed ending is added.
For example:
save → saved
hurry → hurried
permit → permitted
clap → clapped
These verbs are still regular.
A spelling adjustment does not make a verb irregular when it follows the normal spelling conventions for adding the regular -ed ending.
Consider hurry:
The driver hurried back to the car.
He had hurried because it was starting to rain.
Both the past form and past participle are hurried, so the verb remains regular even though y changes to i.
What Makes a Verb Irregular?
An irregular verb does not use the standard regular -ed pattern for its past form, past participle, or both.
There is more than one way this can happen.
Some verbs use the same irregular form for V2 and V3:
seek → sought → sought
Others have different past and past participle forms:
fly → flew → flown
Some stay unchanged:
set → set → set
So irregular verbs do not share one alternative rule. Their forms can change in several different ways.
How to Tell if a Verb Is Regular or Irregular
The safest way is to check both the past form and the past participle.
Take decorate:
decorate → decorated → decorated
Both forms use the regular -ed ending, so decorate is regular.
Now compare teach:
teach → taught → taught
Neither later form follows the regular -ed pattern, so teach is irregular.
Another example is break:
break → broke → broken
Both V2 and V3 are irregular.
But some verbs show why looking only at V2 can be misleading:
show → showed → shown
The past form showed follows the regular -ed pattern, but the past participle shown does not. That makes show an irregular verb.
So the useful test is not simply:
Does the past form end in -ed?
Instead, check whether both the past form and past participle follow the regular -ed pattern.
If either one does not, the verb is irregular.
For a larger V1, V2, and V3 reference, see the irregular verbs list.
Regular and Irregular Verbs in Sentences
The difference becomes clearer when the forms are used in complete sentences.
Regular Verb: Mail
Elena mailed the parcel on Monday.
Here, mailed is the simple past.
She has mailed the receipt separately.
Here, mailed is the past participle.
The pattern is:
mail → mailed → mailed
Irregular Verb: Draw
Marcus drew the first sketch yesterday.
Drew is the simple past.
He has drawn three more sketches since then.
Drawn is the past participle.
The pattern is:
draw → drew → drawn
Regular verbs commonly use the same -ed form for V2 and V3. Irregular verbs may use a different V2, a different V3, or both.
The simple past tense explains in more detail how past forms such as mailed and drew work in sentences.
Irregular Verbs Can Still Share Patterns
Irregular does not mean completely patternless. Some irregular verbs change in similar ways.
For example:
sleep → slept → slept
sweep → swept → swept
Another pair has related vowel changes:
grow → grew → grown
throw → threw → thrown
Some verbs remain unchanged:
cast → cast → cast
broadcast → broadcast → broadcast
These similarities can make groups of irregular verbs easier to recognize, but they are not universal formation rules. A pattern that works for one group cannot automatically be applied to every other irregular verb.
That is why unfamiliar irregular forms are usually learned or checked individually rather than created from a single rule.
Can a Verb Have Regular and Irregular Variants?
Yes. Some English verbs have both a regular -ed form and an established irregular alternative.
For example:
burn → burned / burnt
dream → dreamed / dreamt
learn → learned / learnt
Both forms can be correct.
Compare:
The fire burned for several hours.
By morning, the logs had burnt down to ash.
Variation can depend on region, context, or preference. American English tends to favor forms such as burned, dreamed, and learned, while burnt, dreamt, and learnt remain common in British English and other varieties.
Some verbs therefore have a regular -ed form alongside an established irregular alternative.
Does an Irregular Verb Have Irregular Forms Everywhere?
No. Calling a verb irregular does not mean every form of that verb is unusual.
Compare the regular verb repair with the irregular verb write:
| Verb Form | Regular Verb: repair | Irregular Verb: write |
|---|---|---|
| Base form | repair | write |
| Past form | repaired | wrote |
| Past participle | repaired | written |
| -ing form | repairing | writing |
| Third-person singular present | repairs | writes |
The important irregularity appears in the past and past participle:
write → wrote → written
Its -ing form, writing, and third-person singular present form, writes, follow the usual patterns for those forms.
So the labels regular and irregular mainly describe how a verb forms its past and past participle. They do not mean that every form of an irregular verb must be unusual.
The detailed V1 V2 V3 V4 V5 verb forms page explains those five forms separately.
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