In the Germanic languages, weak verbs are by far the largest group of verbs, and are therefore often regarded as the norm (the regular verbs). They are distinguished from the Germanic strong verbs by the fact that their past tense form is marked by an inflection containing a /t/, /d/, or /ð/ sound (as in English I walk~I walked) rather than by changing the verb's root vowel (as in English I rise~I rose).

Whereas the strong verbs are the oldest group of verbs in Germanic, originating in Indo-European, the weak verbs arose as an innovation in proto-Germanic. Originally the weak verbs consisted of new verbs coined from pre-existing nouns (for example the noun name was turned into the verb to name), or coined from strong verbs to express the sense of causing the action denoted by that strong verb (for example the strong verb to rise was turned into the weak verb to raise).

However, over time, the weak verbs have become the normal form of verbs in all Germanic languages, with most strong verbs being reassigned to the weak class. For example, in Old English the verb to lock (lūcan) was strong (present tense ic lūce 'I lock', past tense ic lēac 'I locked'), but has now become weak. This transition is ongoing. For example, the English verb to cleave currently exists in both a conservative strong form (past tense I clove) and an innovative weak form (past tense I cleaved).

In Germanic languages, weak verbs form their preterites and past participles by means of a dental suffix, an inflection that contains a /t/ or /d/ sound or similar. (For comparative purposes, they will be referred to as a dental, but in some of the languages, including most varieties of English, /t/ and /d/ are alveolar instead.) In all Germanic languages, the preterite and past participle forms of weak verbs are formed from the same stem.

Historically, the pronunciation of the suffix in the vast majority of weak verbs (all four classes) was [ð] but, in most sources discussing Proto-Germanic, it is spelled ⟨d⟩ by convention. In the West Germanic languages, the suffix hardened to [d], but it remained a fricative in the other early Germanic languages (Gothic and often in Old Norse).

In the English language, the dental is a /d/ after a voiced consonant (loved) or vowel (laid), a /t/ after a voiceless consonant (laughed), and /ɪd/ after the dentals/alveolars /t/ and /d/ themselves, but English uses the suffix spelling ⟨ed⟩ regardless of pronunciation, with the exception of a few verbs with irregular spellings.

In Dutch, /t/ and /d/ are distributed as in English provided there is a following vowel. When there is no following vowel, terminal devoicing leads to the universal /t/. Nevertheless, Dutch still distinguishes between the spellings in ⟨d⟩ and ⟨t⟩ even in final position: see the 't kofschip rule.

In Afrikaans, which descends from Dutch, the past tense has fallen out of use altogether, and the past participle is marked only with the prefix ge-. Therefore, the suffix has disappeared along with the forms that originally contained it.