# Design the Twitter timeline and search
*Note: This document links directly to relevant areas found in the [system design topics](https://github.com/donnemartin/system-design-primer#index-of-system-design-topics) to avoid duplication. Refer to the linked content for general talking points, tradeoffs, and alternatives.*
**Design the Facebook feed** and **Design Facebook search** are similar questions.
## Step 1: Outline use cases and constraints
> Gather requirements and scope the problem.
> Ask questions to clarify use cases and constraints.
> Discuss assumptions.
Without an interviewer to address clarifying questions, we'll define some use cases and constraints.
### Use cases
#### We'll scope the problem to handle only the following use cases
* **User** posts a tweet
* **Service** pushes tweets to followers, sending push notifications and emails
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