How have dictionaries changed over the years?
The very earliest dictionaries of English were actually glossaries that translated Latin words into Old English, the form of English spoken before about 1100 AD.
The monolingual dictionary (i.e. one that lists English words and gives definitions in English) didn't appear until 1600 - so Shakespeare did much of his work without even the possibility of looking anything up. For the first century or so, these dictionaries only defined 'hard words'. It wasn't until the 18th century that dictionaries grew and included most meanings of common, everyday words; during that century most of the features we associate with dictionaries first appeared, such as pronunciations, etymologies, and parts of speech.
In the nineteenth century dictionaries of English began to attempt to cover the whole vocabulary of the language and in the twentieth century they became still more inclusive, covering types of language that had not previously been considered appropriate, for example slang, regional words, or technical jargon. Collections of word usage were built up, largely on paper slips or index cards, as the basis for revising existing dictionary entries or creating new ones.
With the arrival of computer technology, it became possible to use electronic databases as the source of language evidence, rather than piles of index cards or slips. Dictionaries are now based on the close analysis of how words behave in real, natural language: behind every Oxford Dictionary entry are genuine examples of the word in use - often hundreds and thousands of them - which have been analysed by lexicographers using specially developed software so as to find out information about the typical behaviour of the word in question. Print dictionaries have been joined by dictionaries in electronic form: these are often enriched with many additional features, such as sound recordings or sophisticated links to other related material.
It seems likely that by the middle of this century, if not before, all dictionaries will be in electronic form. This means that limitations of space, which have always been a serious issue for lexicographers and dictionary publishers, will be much less important. Dictionaries will be able to include more material: more words and definitions, interactive features, and multimedia content such as images, sound, and video. They will also be updated much more rapidly than ever before. But the general idea of a dictionary - a resource that provides explanations of words and how they are used - will probably remain the same.