Grammar detail: other forms of です

other forms of です

My current mastery of this grammar:

In most everyday conversations, です is the form of the verb 'to be' you will encounter at the end of sentences. です is the equivalent of the ます form, ie the normal polite form used in speech, or at the end of written sentences.

The plain form, used in embedded clauses or casual speech, is だ. The past form of だ is だった.

The three other forms you will commonly encounter are である, であります and でございます:

である is a more formal version of だ. In other words, it is a plain form, rather than a polite form, but it is more 'official' sounding. In speech, it might be used by a politician or other senior person in place of です at the end of a sentence. In written Japanese, it would be the typical form in for example a Wikipedia article.
であります is the polite form of である. It would be used by a speaker who needs to be both formal (such as when speaking in a formal setting, eg giving a speech, talking to a senior official), and polite (such as when the speaker is addressing someone more senior).
でございます is the humble form. Compared to であります, this has the effect of elevating the relative status of the listener (or lowering the relative status of the speaker). Most commonly this might be used by a waiter speaking to a customer. (でございます is the masu form of でござる, an older form which you will still hear in samurai dramas. でござる is formed from で + ござる, which is a politer form of ある.)

Each of these forms may also be encountered with a も after the で (eg, でもある, でもあります). The も carries its usual meaning 'too, also'. This example illustrates several of these forms together:

は、

であるだけではなく、

な

でもあります。
Besides being a statesman, he is a well-known painter.

Negative forms

Several negative forms also exist.

ではない is the most common negative form of the plain form だ.
でない is sometimes used instead of ではない. The は in ではない actually functions like the particle marker は, which leads to a subtle difference between the two forms.
じゃない is increasingly used, especially in colloquial speech, instead of both forms.
ではありません is the polite negative form
じゃありません is a hybrid 'casual polite form' - casual, but still with the intention of being polite

Volitional forms

The two main volitional forms are:

だろう - the plain form
でしょう - the polite form

Te form

A polite て form of です also exists: でして. This is often used as a polite alternative to です: ending a sentence with the て form is a way to 'soften' the sentence.

はしばらく、

していたものでしてね
It is because I was leading a secluded life for a while.

Source: https://japanese.stackexchange.com/questions/11256/what-does-ものでして-mean ⇗

More information / references

http://japanese.stackexchange.com/questions/36305/when-to-use-である-vs-であります ⇗
https://japanese.stackexchange.com/questions/19662/when-does-it-make-sense-to-use-でない ⇗
https://japanese.stackexchange.com/questions/28678/だけでなく-and-だけじゃなくて ⇗