Imperfective aspect for repeated action

When describing repeated actions or habits (opakování), the imperfective aspect is the standard choice for the past, present, and future. However, perfective verbs can also be used with words like vždycky or každý den in their past and present forms to emphasize the successful completion of each individual instance in a series. This is primarily used when narrating a sequence of consecutive actions (where one action must finish before the next begins). Note that while perfective verbs conjugated in the present tense normally express the future, using them for a present habit is a specific exception. This occurs most frequently in subordinate clauses of time or condition, especially those starting with když (e.g., Když přijde domů, vždycky si sedne. – When he comes home, he always sits down.).

1. Forming Aspect Pairs
The most fundamental way aspect pairs are formed is by adding a prefix to an imperfective base to create a perfective verb (e.g., dělat → udělat). Alternatively, many imperfective verbs are derived from perfective verbs using suffixes like -ovat, -ávat, -vat, -et/-ět, or -at (e.g., koupit → kupovat; dát → dávat; skočit → skákat; prohlédnout → prohlížet), or by lengthening or mutating the stem vowel, which is often accompanied by a change in the infinitive suffix (e.g., vybrat → vybírat; zavřít → zavírat).

2. Trigger Words
Habits are usually accompanied by adverbs of frequency, such as:

• často (often)
• každý den (every day)
• vždycky (always)
• obvykle (usually)

3. Iterative Verbs (Násobná slovesa)
To strongly emphasize a routine or habit, Czech uses a dedicated class of imperfective verbs called iterative verbs. These are formed by adding suffixes like -ívat, -ávat, or -vávat to an existing imperfective verb (e.g., dělat → dělávat; být → bývat; kupovat → kupovávat). They are frequently used in the past tense to reminisce about past habits, translating directly to 'used to' or 'would' in English. While iteratives are mostly for past habits, the verbs bývat and mívat are frequently used in the present tense to mean 'usually is' and 'usually has'. Note that iterative verbs are strictly imperfective and cannot take prefixes to form perfective pairs (e.g., dělávat cannot become udělávat). However, you will often see prefixed verbs ending in -ávat (like vydělávat or předělávat). These are not prefixed iteratives, but rather secondary imperfective verbs derived from perfective verbs (e.g., vydělat → vydělávat).

Note: Verbs of motion have their own unique sub-system for repeated actions, distinguishing between one-way and repeated trips. For repeated trips or habits, you must strictly use the multidirectional (indeterminate) verb (e.g., chodit, jezdit) rather than the unidirectional (determinate) verb (e.g., jít, jet).