The Germanic language family is one of the language groups that resulted from the breakup of Proto-Indo-European (PIE). It in turn divided into North, West and East Germanic groups, and ultimately produced a large group of mediaeval and modern languages, most importantly: Danish, Norwegian, and Swedish (North); English, Dutch and German (West); and Gothic (East, extinct).
The Germanic verb system lends itself to both descriptive (synchronic) and historical (diachronic) comparative analysis. This overview article is intended to lead into a series of specialist articles discussing historical aspects of these verbs, showing how they developed out of PIE, and how they came to have their present diversity.
The Germanic verb system carried two innovations over the previous Proto-Indo-European verb system:
Simplification to two tenses: present (also conveying future meaning) and past (sometimes called "preterite" and conveying the meaning of all of the following English forms: "I did, I have done, I had done, I was doing, I have been doing, I had been doing").
Development of a new way of indicating the preterite and past participle, using a dental suffix.
Later Germanic languages developed further tenses periphrastically, that is, using auxiliary verbs, but the constituent parts of even the most elaborate periphrastic constructions are still only in either present or preterite tenses (or non-finite forms: cf I would have been doing, an English conditional perfect progressive with would in the preterite, the other three parts being non-finite).
Germanic verbs fall into two broad types, strong and weak. Elements of both are present in the preterite-present verbs. Despite various irregularities, most verbs fall into one of these categories. Suppletive verbs are completely irregular, being composed of parts of more than one Indo-European verb. There is one verb (*dōną 'to do') that is in a category of its own, based on an Indo-European "athematic" form, and having a "weak" preterite but a "strong" passive participle.