Word clouds are popular in presentations, on webpages, used in books, lessons, etc., as attractive assemblies of words. The essential feature of a word cloud is that the more frequent a word is in the input text, the bigger it appears in the cloud. And the cloud in this context is a graphic containing the key words in the text that the user provides. For one thing, this allows you to see what the key words are, which is useful if you are preparing to read a text whose key words you are unfamiliar with. And it can give you some idea of what a text is about.
The best known cloud-maker is Wordle. Concordle, despite not producing word clouds as fancy as Wordle's, it offers some important features of interest to language teachers and students.
Key Feature of Concordle
The key difference between Concordle and other cloud-makers is that every word is clickable. The click generates a list of the contexts (a concordance) in which the clicked-on word appears. This word, the "node", is centre aligned, a format known in corpus work as Key Word in Context (KWIC). These contexts provide data for a range of linguistic observations, which can be very instructive for teachers and students alike.
Concordle's corpus is the text that you have generated your word cloud from. This differs from most corpora, which are large collections of many texts, typically running to millions of words. In Concordle, you see your key words in the context of the input text only.