Adverbs

Adverbial expressions appear as single words or in the form of phrases. In either case, their function is the same: to explain how, when, where, or why about an action or event. Below is a list of some commonly used single-word adverbs:
                         neulich                                                        recently
                         niemals                                                       never
                         oft                                                                often
                         telefonisch                                                 by telephone
                         wahrscheinlich                                          probably


And the following are adverbs that appear in phrase form:

am schnellsten                                           the fastest

das ganze Jahr                                           the whole year

im Winter                                                    in the winter

mit dem Zug                                               by train

vor einer Woche                                         a week ago

With the exception of the phrase das ganze Jahr, each of the examples in the above list is 
a prepositional phrase. A large number of adverbial phrases are, indeed, prepositional phrases.
Like das ganze Jahr, many adverbial expressions that tell when something occurs are given in the accusative case. For example:

                      Ich war den ganzen Tag in Bremen.         I was in Bremen all day.
                      Onkel Peter kommt nächste Woche.        Uncle Peter is coming next week.

Adverbs of Degree

The function of adverbs is not as simple as modifying a verb, an adverb, or an adjective, because adverbs modify in a variety of ways. Some merely qualify the degree of an adverb or adjective used in a sentence. For example:
außerordentlich              exceptionally              relativ              relatively
etwas                                 somewhat                    sehr                 very
fast                                     almost                          total                 totally
ganz                                   quite                             völlig                completely
gewöhnlich                      usually                          wenig               little
nur                                     only                              ziemlich           rather
recht                                  quite, rather               zu                       too

Consider the meaning of the preceding adverbs. They generally would not stand alone but would be used to modify another word. Let’s look at some example sentences:

Die Studentin muss sehr fleißig arbeiten.               The student has to work very diligently.
Seine Rede war außerordentlich langweilig.          His speech was exceptionally boring.
Wir hatten in diesem Jahr einen relativ                  We had a relatively warm winter this year.  warmen Winter.                                                                                            
verb     + adverb    Er singt gut.
adverb + adverb         Er singt sehr gut.
adverb + adjective Es ist ein ziemlich altes Haus.

Modal adverbs

Some adverbs portray an attitude toward a statement or are part of the answer to a yes or no ques-tion. Germans call such adverbs modale Adverbien (modal adverbs). They comment on some occurrence or show a point of view. Some commonly used adverbs of this type are
auf jeden Fall           in any case           selbstverständlich           naturally
bestimmt                  definitely              sicher                                 surely, safely
gewiss                       certainly                tatsächlich                        actually, really
hoffentlich               hopefully              unbedingt                          absolutely
leider                        unfortunately      wahrscheinlich                 probably
natürlich                  naturally              wirklich                              really
ohne Zweifel           without a doubt

Such adverbs are often used in an elliptical phrase, meaning that they can stand alone, 
because the content of the response is understood. For example:

—Kann Erik uns helfen? — Can Erik help us?
—Selbstverständlich. — Naturally.
—Haben sie genug Geld, um ins Kino zu gehen? —Do they have enough money to go to the movies?
—Hoffentlich. — Hopefully. (I hope so.)
—Ist deine Mutter wieder gesund? —Is your mother well again?
—Leider nicht. — Unfortunately, not.

In addition, adverbs of this type are used in complete sentences like other adverbs:
Es ist wirklich kalt geworden.                                                It’s gotten really cold. 
Der Kranke wird wahrscheinlich heute abend sterben.   The patient will probably die this                                                                                                                           evening
Adverbs and word order

Three major categories of adverbs are those that show time, manner, and place. They can be single words or phrases and are found in abundance in the language. Some examples:
Time Manner
damals                 then                         anders               differently
gestern                 yesterday               dadurch             through it, as a result
heute                    today                       irgendwie          somehow
im Sommer         in summer             langsam             slowly
lange                     long                         mit dem            Bus by bus
manchmal           sometimes             mit Müh und    Not with great difficulty
morgen                 tomorrow              schnell               fast
nächste Woche   next week               sorglos               carelessly
oft                          often                       telefonisch        by telephone
selten                    seldom                    vorsichtig         carefully

Adverbs of place can describe location at a place or motion to a place. For example:

Location:	Er wohnt hier.	He lives here.
Motion:	Er kommt hierher.	He comes here.
Location:	Sie bleibt zu Hause.	She remains at home.
Motion:	Sie muss nach Hause gehen.	She has to go home.
Location:	Ich arbeite in der Stadt.	I work in the city.
Motion:	Ich fahre in die Stadt.	I drive to the city.

Adverbs cannot be placed in a German sentence at random. Adverbs that describe place appear last in a sentence. Adverbs of manner precede them. Adverbs of time precede adverbs of manner. And if an adverb that describes a point of view is in a sentence, it will precede all the others. For example:

Place: Tina wird nach Bonn fahren.                                    Tina will go to Bonn.
Manner: Tina wird mit dem Auto nach Bonn fahren.    Tina will go to Bonn by car.
Time: Tina wird am Freitag mit dem              Tina will go to Bonn by car on Friday.
Auto nach Bonn fahren
Point of view: Tina wird leider am Freitag mit           Unfortunately, Tina will go to Bonn
                               dem Auto nach Bonn fahren.               by car on Friday.

The position of adverbs in a sentence is generally:
point of view + time + manner + place

Adverbs in the comparative and superlative

Just like adjectives, adverbs have comparative and superlative forms. Unlike adjectives, however, adverbs do not require various endings that reflect gender, case, and number. Their only declen-sional form appears in the superlative, with the preposition am (an dem). Let’s look at some examples:

Positive                              Comparative                      Superlative
gut                good, well        besser                 better           am besten               best
schnell         fast                    schneller            faster           am schnellsten       fastest
langsam      slowly                langsamer         slower          am langsamsten    slowest
schlecht      badly                  schlechter         worse           am schlechtesten   worst