The infinitive is the base form of the verb and denotes the action without person, tense or number. In German it usually ends in -en or, less commonly, in -n, as with Weak Verbs like machen or in forms like sein and haben. Unlike languages with conjugation paradigms on -ar, -er, -ir, German has no such system, but mainly uses endings -en and -n. The infinitive is also the form that appears in dictionaries and is the form that combines with other verb forms.

Weak verbs form their forms regularly and are the simplest starting point for infinitive use. The infinitive remains unchanged, the preterite usually ends in -te, and the Past Participle II is formed with the stem and -t, as with Weak Verbs. This regularity makes weak verbs especially important for the construction of compound verb forms.

GedankeIdea	BeispielExample
Der Infinitiv bleibt als Grundform erhalten.The infinitive remains as the base form.	Ich will machen, dass alles passt, weil der Plan klar ist.I want to make sure everything fits, because the plan is clear.
Das Präteritum schwacher Verben endet meist auf te.The preterite of weak verbs usually ends in -te.	Gestern machte er die Aufgabe, weil die Zeit knapp war.Yesterday he did the task because time was short.
Das Partizip II entsteht mit Stamm und t.The Past Participle II is formed with the stem and -t.	Er hat das Fenster geöffnet, weil es warm war.He has opened the window because it was warm.

Strong verbs often show in the infinitive the same base form as weak verbs, but their other forms follow a different pattern. In the preterite, the stem vowel often changes, and the Past Participle II often ends in -en, as with Strong Verbs. This irregularity is a central feature of strong verbs and concerns especially common verbs like sehen, gehen and nehmen.

GedankeIdea	BeispielExample
Der Stammvokal kann sich im Präteritum ändern.The stem vowel may change in the preterite.	Er sah den Zug, bevor er losfuhr.He saw the train before he pulled away.
Das Partizip II endet oft auf en.The Past Participle II often ends in -en.	Sie hat den Brief gesehen, obwohl es spät war.She has seen the letter, although it was late.
Der Infinitiv bleibt trotzdem die Grundform.The infinitive remains the base form nonetheless.	Wir gehen heute nach Hause, wenn die Arbeit fertig ist.We're going home today once the work is finished.

Mixed verbs combine regular and irregular properties and are therefore particularly noticeable. They usually form the preterite irregularly, but the Past Participle II regularly with ge- and -t, as with Mixed Verbs. The verb bringen is a typical example, because it shows brachte in the preterite and gebracht in the Past Participle II.

GedankeIdea	BeispielExample
Das Präteritum ist unregelmäßig.The Preterite is irregular.	Er brachte die Tasche nach oben, bevor er ging.He brought the bag upstairs before he left.
Das Partizip II bleibt regelmäßig.The Past Participle II remains regular.	Sie hat das Paket gebracht, obwohl es schwer war.She has brought the package, although it was heavy.
Gemischte Verben verbinden zwei Muster.Mixed Verbs connect two patterns.	Wir dachten an dich, als der Brief kam.We thought of you when the letter came.

The auxiliary verbs sein, haben and werden form compound tenses, the passive and future forms. They often occur together with an infinitive or participle and are therefore important for sentence structure. The auxiliary verbs carry often little own meaning, but they govern the grammatical form of the entire sentence.

GedankeIdea	BeispielExample
sein bildet oft Bewegungs und Zustandswechsel.sein often marks movement and state changes.	Er ist gegangen, nachdem das Gespräch endete.He has left after the conversation ended.
haben bildet viele Perfektformen.haben forms many Perfect tenses.	Sie hat gelacht, weil die Geschichte lustig war.She has time, although she works a lot.
werden markiert Zukunft und Passiv.werden marks future and passive.	Morgen wird gearbeitet, wenn alle da sind.Tomorrow work will be done when everyone is here.

Modal verbs such as can, must, may, should, will and like stand with an infinitive without to. They alter the meaning of the full verb and express possibility, necessity, permission, obligation, will or preference. The main verb remains in the infinitive at the end of the clause.

GedankeIdea	BeispielExample
Der Infinitiv steht ohne zu.The infinitive stands without to.	Ich kann kommen, wenn ich früher fertig bin.I can come if I finish earlier.
Das Modalverb steht in der flektierten Form.The modal verb appears in the inflected form.	Sie muss arbeiten, weil die Frist heute endet.She must work because the deadline ends today.
Das Vollverb bleibt im Infinitiv am Satzende.The full verb remains in the infinitive at the end of the clause.	Wir wollen bleiben, obwohl es schon spät ist.We want to stay, although it is already late.

Separable verbs consist of a prefix and stem, and both parts can separate in the sentence. In the infinitive the prefix and stem stand together, but in an infinitive with to the 'zu' stands in the middle, as in anzufangen, which is decisive for the construction with Separable Verbs. This position shows that the 'zu' attaches to the entire infinitive and does not simply occur before it.

GedankeIdea	BeispielExample
Der Infinitiv zeigt Präfix und Stamm zusammen.The infinitive shows prefix and stem together.	Er will anfangen, bevor der Regen beginnt.He wants to start before the rain begins.
Im Infinitiv mit zu steht zu in der Mitte.In the infinitive with zu, zu stands in the middle.	Sie hofft, anzufangen, wenn alle Plätze frei sind.She hopes to begin when all seats are free.
Das Präfix bleibt im Infinitiv erkennbar.The prefix remains recognizable in the infinitive.	Wir versuchen aufzuräumen, obwohl wenig Zeit bleibt.We try to tidy up, although little time remains.

Inseparable verbs keep their prefix firmly attached to the stem. In the Past Participle II there is therefore no ge-, and forms like verstehen or bekommen show this fixed pattern, which contrasts closely with Separable Verbs. The infinitive itself remains simply as the connected base form.

GedankeIdea	BeispielExample
Das Präfix bleibt fest verbunden.The prefix remains firmly attached.	Er versteht die Frage, bevor er antwortet.He understands the question before he answers.
Im Partizip II steht kein ge.In the Past Participle II there is no ge-.	Sie hat den Brief bekommen, obwohl niemand klingelte.She has received the letter, although no one rang.
Der Infinitiv bleibt unverändert.The infinitive remains unchanged.	Wir versprechen, das Problem zu lösen, wenn es nötig ist.We promise to solve the problem if it is necessary.

The infinitive field includes several non-finite forms used without person and often without time reference. The infinitive with to serves as a dependent verb form, Participle I ends in -end, and Participle II forms compound tenses, the passive and other periphrases; for this, Participles is the appropriate continuation. Also the nominalized verb belongs here, because an infinitive can be capitalized as a noun and then needs an article.

GedankeIdea	BeispielExample
Der Infinitiv mit zu ist eine abhängige Verbform.The infinitive with to is a dependent verb form.	Es ist wichtig, zu lernen, wenn die Prüfung näherkommt.It is important to learn, as the exam approaches.
Das Partizip I endet auf end.Participle I ends in -end.	Die singende Menge hörte nicht auf, als die Tür sich schloss.The singing crowd did not stop when the door closed.
Der Infinitiv kann als Substantiv auftreten.The infinitive can occur as a noun.	Das Essen ist fertig, bevor der Besuch kommt.The meal is ready before the visitor arrives.

Periphrastic constructions connect an auxiliary or modal verb with a non-finite verb form. The infinitive with zu stands after certain verbs, modal verbs stand with infinitive without zu, lassen can be followed by an infinitive, and werden forms the future with the infinitive. These structures show that the infinitive in German is often the core of larger verb groups.

GedankeIdea	BeispielExample
zu markiert den abhängigen Infinitiv.to marks the dependent infinitive.	Er beginnt, zu lesen, sobald er Ruhe hat.He begins to read as soon as he has a moment of quiet.
Modalverben stehen mit Infinitiv ohne zu.Modal verbs stand with infinitive without zu.	Wir dürfen gehen, wenn die Arbeit beendet ist.We may go, because the work is finished.
werden bildet das Futur mit Infinitiv.werden forms the future with infinitive.	Morgen wird kommen, wer heute nicht da ist.Tomorrow someone will come who is not here today.

In the early learning stage, sein, haben and werden are encountered especially often, since they occur as auxiliary and full verbs. Also can, must, may, should, will and like come into play, since they govern the infinitive construction without to. Together with gehen, sehen, machen, bringen, verstehen and bekommen they form the practical core of the German verb forms and their usage.

GedankeIdea	BeispielExample
sein ist hochfrequent und unregelmäßig.sein is highly frequent and irregular.	Er ist müde, weil der Tag lang war.He is tired because the day was long.
haben ist zentral für Perfektformen.haben is central for perfect forms.	Sie hat Zeit, obwohl sie viel arbeitet.She has time, although she works a lot.
werden ist wichtig für Zukunft und Passiv.werden is important for future and passive.	Wir werden gehen, wenn das Licht ausgeht.We will go when the light goes out.