Many mathematicians adopted blackboard bold, but many others still prefer to use bold. In textbooks, however, the situation is not so clear cut. In the 1960s and 1970s, blackboard bold spread quickly in classrooms and is now widely used in the English- and French-speaking worlds. See Wikipedia's guide to writing better articles for further suggestions.
Please improve the article by adding more descriptive text and removing less pertinent examples. This section may contain indiscriminate, excessive, or irrelevant examples.