The examiners will therefore assess your Abstract both as part of your thesis, and as a potentially independent document.
Alternatively it can be useful to write the abstract earlier on, as an aid to identifying the crucial main thread of your research, its purpose, and its findings, which could then guide the structure of the dissertation.
Attending to the very restrictive word / space limit, while at the same including all the relevant material is quite a challenge.
The introduction has two main roles: This can lead logically into a clear statement of the research question(s) or problem(s) you will be addressing.
In addition to the research context, there may be other relevant contexts to present for example: It can be difficult to identify the best order for sections in this chapter because the rationale for your choice of specific research question can be complicated, and there may be several inter-linked reasons why the research is needed.