In software quality assurance, what is a walkthrough and what is an inspection, and how do these two static review techniques differ from each other in purpose and formality?

Introduction / Context:
Walkthroughs and inspections are classic static testing techniques where software artefacts are examined without executing the program. Interviewers frequently ask this question to confirm that a tester understands different levels of formality in reviews and how these reviews help find defects early in the life cycle, even before coding or test execution starts.

Given Data / Assumptions:
- The artefacts may include requirements, design documents, code or test cases.
- Walkthroughs and inspections both try to identify defects, ambiguities and missing information.
- The main difference concerns formality, roles and use of checklists.
- No numerical values are involved; only conceptual understanding is required.

Concept / Approach:
A walkthrough is usually initiated and driven by the author of the document or code. The author presents the material to peers, explains logic and design choices, and listens to feedback. It is less formal, may or may not use strict entry and exit criteria, and minutes might be lightweight. An inspection, on the other hand, is a highly structured review. It uses defined roles such as moderator, reader, recorder and reviewers, and typically uses checklists and metrics. Inspections often have measurable defect density goals and documented procedures.

Step-by-Step Solution:
Step 1: Identify that the question is about static review techniques. Step 2: Recall that walkthroughs are informal, explanation oriented sessions led by the author. Step 3: Recall that inspections are formal, with planned meetings, checklists, roles and follow up actions. Step 4: Compare each option to see which one captures informal author led review versus formal peer inspection. Step 5: Option a mirrors the standard ISTQB style definition and therefore is the correct choice.

Verification / Alternative check:
As an alternative check, ask whether defects discovered in each type of review are generally recorded and used for metrics. In inspections, defect logs and statistics are essential. In walkthroughs, they may be recorded but the process is more flexible. This again confirms that the primary difference is formality and structure, which option a correctly states.

Why Other Options Are Wrong:
Option b is incorrect because these activities are normally done by project team members and sometimes stakeholders, not exclusively customers or end users. Option c falsely claims that walkthroughs are fully automated and that inspections avoid documents, which is not true. Option d ignores well documented distinctions between the two techniques and is therefore incorrect.

Common Pitfalls:
A frequent mistake is to think that walkthroughs are unplanned chats. Even though they are informal, an agenda and sample scenarios should still be prepared. Another pitfall is assuming inspections are only useful for code; in fact, they are extremely powerful for requirements and design as well. Testers should select the right technique depending on risk, team maturity and available time.

Final Answer:
A walkthrough is an informal review led by the author to explain the work product, whereas an inspection is a formal, checklist based peer review with defined roles, entry and exit criteria.