---
title: "Activity versus event"
subject: "ICT Project Management"
chapter: 8
key: "semester_7/ict_project_management:activity-vs-event"
source: https://www.bctengineer.com/q/semester_7/ict_project_management/activity-vs-event
site: BCT Engineering
---

# Activity versus event

ICT Project Management · Chapter 8: Project Time Management

- Asked in: year not given
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/ict_project_management/activity-vs-event
- Whole chapter: https://www.bctengineer.com/md/semester_7/ict_project_management/chapter-8

## Question

What do you mean by activity? How is it different from an event?

## Short answer

An activity is a work task that consumes time and resources, having duration. An event is a point in time marking start or completion, with zero duration and no resources. In AOA networks, activities are arrows and events are nodes.

## Answer

An **activity** is a task or element of work performed during the project. It consumes time and resources, and has a duration. An **event** is a point in time that marks the start or completion of one or more activities; it consumes no time or resources.

| Basis | Activity | Event |
|---|---|---|
| Meaning | Work to be done | A point in time showing a status |
| Time | Consumes time (has duration) | Takes zero time (instant) |
| Resources | Needs resources and cost | No resources |
| Network representation | Arrow in AOA (activity on arrow); node in AON (activity on node) | Node/circle in AOA |
| Nature | Process | Accomplishment/milestone |
| Naming | Verb: "Design database" | Past tense: "Database designed" |
| Example | Writing code | Code completed |
| Emphasised in | CPM (activity-oriented) | PERT (event-oriented) |

```text
(1) ---- Design database ----> (2)
 event       activity           event
 "Design     (duration 5 days)  "Design
  started"                       complete"
```

#### Related terms
- **Milestone**: a significant event, with zero duration.
- **Dummy activity**: shows a dependency with no duration or resources (dashed arrow).
- **Predecessor and successor**: activities that must occur before or after.

#### Explanation
- In an AOA network, nodes represent events and arrows represent activities. Activity A from event 1 to event 2 starts when event 1 occurs, and when it finishes, event 2 occurs.
- Event 2 occurs only when all activities leading into it finish.
- In PERT, scheduling is event-oriented (events have earliest and latest expected times); in CPM, it is activity-oriented.

**Example:** "Install servers" is an activity taking 3 days. "Servers installed" is an event marking the milestone.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is true of an activity compared with an event?
   A. Both consume resources
   B. Neither has a duration
   C. An event consumes time; an activity does not
   D. An activity consumes time and resources; an event does not
   Answer: D. Activities have duration and need resources, while events are instants marking start or completion. (Key point: Time and resources)

2. In an Activity-on-Arrow network, how are activities and events shown?
   A. Activities as nodes and events as arrows
   B. Activities as arrows and events as nodes
   C. Both as nodes
   D. Both as arrows
   Answer: B. In AOA, arrows are activities and nodes (circles) are events. (Key point: AOA representation)

3. Which pair is correctly named as activity and event?
   A. 'Test passed' and 'Test passed'
   B. 'Write code' and 'Code completed'
   C. 'Writing' and 'Write'
   D. 'Code completed' and 'Write code'
   Answer: B. Activities use verbs; events use past tense showing accomplishment. (Key point: Naming)

## Related in ICT Project Management

- [Project cost versus product cost](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Aproject-vs-product-cost) — ICT Project Management, chapter 9

## Related in other subjects

- [Event management system summary and class diagram](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Aoems-executive-summary-class-diagram) — Object Oriented Analysis and Design, chapter 2
- [Optical activity; tartaric acid stereoisomers](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aoptical-activity-tartaric) — Engineering Chemistry, chapter 9
- [Event types; airport weapon detection Bayes](https://www.bctengineer.com/question.md?key=semester_5%2Fprobability_and_statistics%3Aairport-weapon-bayes) — Probability and Statistics, chapter 1
- [Sectoring versus cell splitting for capacity](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Asectoring-vs-cell-splitting) — Wireless Communication, chapter 2, asked 2×