approximately 200, can be considered as quasi complete. It can be used (by students and teachers alike) to find the right expression. English transition words are essential, since they not only connect ideas, but also can introduce a certain shift, contrast or opposition, emphasis or agreement, purpose, result or conclusion, etc. in the line of argument.
The transition words and phrases have been assigned only once to somewhat artificial categories, although some words belong to more than one category.
There is some overlapping with preposition and postposition, but for the purpose of clarity and completeness of this concise guide, I did not differentiate.