Dutch is used in the countries The Netherlands, Belgium, Suriname, Netherlands Antilles & Aruba, sometimes in Indonesia and some neighbouring parts of Germany and France. But if you speak Standard Dutch you can also hold conversations very easily in Southern Africa, in South Africa and Namibia.
Since the founding of Kaapstad (Cape Town) in 1652 a variety of Dutch was spoken at the Cape, gradually spreading over much of Southern Africa. Since 1806 the political ties were severed and the spoken languages evolved in their own directions, much as English did in the U.S. and French did in Quebec. Some Dutch dialects and Afrikaans are still very close to each other and the differences between Dutch dialects are at least as big as between Dutch and Afrikaans. In fact, until 1925 there was only one written standard legally recognized both in South Africa and in Belgium and the Netherlands.
Unfortunately, this written standard was rather artificial and archaic and did not reflect what people actually spoke. For example the standard still had case endings and three genders (masculine, feminine and neuter). Only certain dialects of Flanders and the southern part of the Netherlands still had at least three genders in the spoken language. The northern Netherlands only had two genders and South Africa only one. The inflectional system was already gradually becoming disused in the Middle Ages, but later grammarians decided that it had to be preserved— even brought back— at all costs. On top of that the spoken language of South Africa had a much simplified verbal system, e.g. it no longer used the simple past tense. There were also numerous differences in pronunciation and semantics.
The discrepancies between the single written standard and what people actually spoke were so large that they created serious educational problems and formed an impediment to social progress both in Africa and in Europe.
This was why the Kollewijn spelling (1891) proposed radical changes for the spelling of the language. It is also known as "Schrijf zoals je praat / Skryf hoe jy praat-spelling" (Write-as-you-talk spelling). In South Africa, where the discrepancies were the most conspicuous, his ideas were implemented in the 1920's with considerable vigor.
In the Netherlands and Belgium (and their colonies) his ideas were dismissed as outrageous and iconoclastic. It was also feared that what had been one language would splinter into many, each of which would be unable to compete in the modern world.
In 1925 Afrikaans was officially recognized as a separate language with its own spelling and grammar, much closer to what people actually spoke. In Europe it was only after the Second World War that the educational and political establishment finally threw in the towel and followed the Afrikaans example. In 1947 the spelling was revised in such a way that case endings (notably the -n in the masculine singular accusative: den) were made optional. Rapidly it disappeared from use. Many silent and superfluous letters were omitted, e.g.:
de menschen wenschen → die mense wens
de boeken van dien aardigen kleinen jongen → die boeke van die aardige klein jong
The reform of 1947 was not quite as sweeping as the one in 1925.
For example the word for at home is still written as thuis (from: te huis) in Dutch, but as tuis in Afrikaans. Similarly, thans (from te hands: now) is written as it is pronounced in Afrikaans: tans.
In part the reluctance to reform had to do with the fact that earlier ideas in Flanders to create a separate standard closer to what was spoken there had largely been abandoned. In Belgium the language was under considerable pressure from a French speaking elite and could ill afford further fragmentation. Despite considerable variety in the spoken language there was clearly a desire to keep the written umbrella unified. This led to increased linguistic cooperation between Flanders and the Netherlands and the creation of the Taalunie.
The ties with South Africa in the mean time had become all but severed because the Apartheid government there - amongst other things - emphasized the uniqueness of the Afrikaans language. In fact in 1961 all linguistic ties were broken. The Netherlands and Belgium increasingly joined the boycott against apartheid. Since 1994 there is a slow process of renewal of ties but the languages have continued to evolve in different directions in the meantime.