# Segments > Group the buckets of one system, such as everything behind checkout, and see them on one overview, one dashboard and one traffic search Source: https://dev.apitraffic.io/docs/segments A segment is a named group of buckets, such as **Checkout** for the storefront, checkout and payments buckets. It holds no data and no settings: it is a saved scope. Every segment opens on a ready-made overview, and reports, dashboards and traffic search can be scoped to a segment instead of one bucket. A segment is read as it is when something runs, so a bucket you add to it tomorrow shows up in every dashboard on it without editing the dashboard. Segments need the **Segments** feature in your plan. Open **Segments** in the **All buckets** sidebar. *The Segments page.* ![The Segments page listing Checkout (payments with 1 service, and storefront) and Mobile (storefront), each with Edit and Delete](https://dev.apitraffic.io/docs/images/segments/segments-list.png) **Who can do what:** everyone on the account sees every segment. Any member can create and change segments. Deleting one is for the person who created it, or an owner or admin. ## Creating a segment **Start a new segment** In **Segments**, click **New segment**. Or open the bucket menu at the top of the app and choose **Add to Segment**, then **New segment with this bucket**. **Name it** Give it a **Name**, optionally a **Description**, and the environment it **Opens in** (production, usually). **Choose its buckets** Tick each bucket to include. A bucket is included as the **Whole bucket**, which covers its services now and any added later, or choose **Some services** and tick the services you want. **Save** Click **Create segment**. The segment's overview opens. *Choosing a segment's buckets and services.* ![New segment: a name, the environment it opens in, and a list of buckets, storefront as the whole bucket and payments narrowed to payments-worker](https://dev.apitraffic.io/docs/images/segments/segment-new.png) Choosing services follows the rules of the bucket's Services page: a service that is later merged into another is read as the service it was merged into, and renames and new names apply to all past traffic. An archived service cannot be newly chosen; one already in the segment stays until you take it out. A service that was deleted is shown as deleted, and saving the segment takes it out. ## Filling a segment with a label rule Instead of ticking every bucket, give a segment a **rule**: "also include everything labelled `system=checkout`". A bucket that gains the label joins the segment, and every dashboard, report and search on it, without anyone editing the segment; a bucket that loses the label leaves it. **Label your buckets** In a bucket's left navigation, select **Bucket settings**, then the **Labels** tab, and add key-value labels such as `system=checkout` or `team=payments`. Keys are lower-case letters, digits, `.`, `_`, `-` or `/`; values are up to 100 characters. A bucket has at most 20 labels. **Label services, if only some belong** A service inherits its bucket's labels and can add its own, on its page in **Services**. Where a bucket and its service set the same key, the bucket's value counts. A service has at most 20 labels of its own. **Give the segment its rule** In **New segment** or **Edit**, under **Rule**, add the labels to match. The form shows the buckets labelled with them now. Every pair must match; a rule has at most 10. *A service's own labels.* ![Labels card on a service page: system=checkout, with Add a label and Save labels](https://dev.apitraffic.io/docs/images/segments/service-labels.png) *A bucket's labels.* ![Bucket settings, Labels tab: system=checkout and team=web, with Add a label and Save labels](https://dev.apitraffic.io/docs/images/segments/bucket-labels.png) What a rule adds: - A bucket labelled with every pair joins as the **whole bucket**. - In a bucket that is not, each service labelled with them (its own labels, or its bucket's) joins, and the bucket is read narrowed to those services. Archived services are not added. - A bucket you chose by hand that the rule also matches reads what either gives it: the whole bucket if either is the whole bucket. The segment's overview names the members the rule added, and in **Edit** they are listed under the rule rather than ticked: they are not saved with the segment, they are read each time it is. *The members a rule adds, named on the overview.* ![Checkout overview header: its buckets, and the line Rule system=checkout naming the checkout, payments and storefront buckets it adds, with Edit and Customize](https://dev.apitraffic.io/docs/images/segments/segment-rule-members.png) *A segment's rule.* ![Edit segment, the Rule card: system=checkout, the buckets labelled with it now, and what the saved rule adds](https://dev.apitraffic.io/docs/images/segments/segment-rule.png) ## Adding a bucket from the bucket menu Open the bucket menu at the top of the app and choose **Add to Segment**. Each segment is listed with **Add**, or with **Holds this bucket** if it already has it. Adding a bucket adds the whole bucket; to choose some of its services, edit the segment. *Adding the current bucket to a segment.* ![The Add to segment dialog listing Checkout (holds this bucket) and Mobile with an Add button](https://dev.apitraffic.io/docs/images/segments/add-to-segment.png) ## The segment overview Every segment opens on the same overview, so it needs no setup. The **time range** and **environment** at the top apply to everything on the page. - **The whole segment:** requests, error rate, p95 latency and, if your plan includes the firewall, firewall blocks, each against the previous period. - **Services:** one row per service in the segment, grouped by bucket (click a bucket to collapse it): requests with a sparkline, error rate, p95, the bucket's last deployment, the instances running now and their Node versions. Click a column heading to sort by it, and a service to open it. - **Requests, errors and p95 by service:** one band or line per service (the busiest eight; on the requests and errors charts the rest are added up as Other), with the deployments of every bucket in the segment marked on the time axis, so "errors rose right after payments deployed" is visible. The deployments are also listed under the charts. - **Top endpoints** across the segment, each with its service, and **top errors**, by service and status code. Each panel is a report on the segment, so its numbers are the same as a report you build yourself with the segment as its scope. When the [Security Center](https://dev.apitraffic.io/docs/security-center) is on for your account, the overview also has a **Security** panel: the segment's security score and its five worst findings, each opening the finding, with a link to the Security Center filtered to the segment. The Security Center reads a segment as whole buckets, so a bucket the segment narrows to some services counts in full, and the panel says so. *A segment's security.* ![The Security panel of the Checkout overview: the score out of 100 with its grade, and the five worst findings, each with its severity](https://dev.apitraffic.io/docs/images/segments/segment-security.png) ## Customize Click **Customize** to copy the overview into a [dashboard](https://dev.apitraffic.io/docs/dashboards) you can change like any other: each panel becomes a saved report on the segment, visible to everyone on the account, and the dashboard opens on the segment with the overview's time range and environment. Customize needs the **Custom reports** feature, and the reports and the dashboard count towards your plan's saved reports and dashboards. The overview itself does not change. ## Segments in reports, dashboards and traffic search - **Reports and dashboards:** the **Bucket** picker lists your segments under **Segments**. A report or dashboard on a segment reads every bucket in it. Group by **Bucket** or by **Service** to split its numbers. - **Security Center:** the **Buckets** menu lists your segments; the score, findings, coverage and posture then cover the segment's buckets. - **Alert routing:** a [notification route](https://dev.apitraffic.io/docs/alerts/routing) can match a segment, so "everything in Checkout goes to #checkout-oncall" stays true as buckets join the segment. - **Embeds:** a [report or dashboard embed](https://dev.apitraffic.io/docs/integrations/embed-reports) can be locked to a segment with `segmentSid`, as it can to a bucket. It reads the segment's buckets each time it runs. - **MCP:** `list_segments` lists them, `get_segment_overview` says how one is doing, and `run_report` takes `scope.segmentSid`, so an agent can answer "what's the error rate across Checkout?". See [MCP tools](https://dev.apitraffic.io/docs/integrations/mcp-tools). - **Traffic search:** search a segment's requests with the [Segments API](https://dev.apitraffic.io/docs/api-reference/segments#search-a-segments-traffic); each request carries its bucket. If your plan stops including Segments, saved reports and dashboards on a segment keep running, and your segments stay listed; creating and changing segments, and new questions across one, need the feature again. ## All services **Services**, in the **All buckets** sidebar, lists every service in every bucket with the same columns as a segment's services table. Choose a bucket or a segment to narrow it, a **Label** to list the services labelled with it (their own labels or their bucket's), and search by service, bucket or Node version, for example `v18` to find every service still on Node 18. *Every service across the account.* ![All services: filters for bucket or segment, time range, environment and search, and the services table grouped by bucket](https://dev.apitraffic.io/docs/images/segments/all-services.png) ## Access People on the account see every bucket, so every segment shows in full. A connection limited to some buckets, such as an MCP connection chosen for some buckets, sees a segment narrowed to those buckets, with a note such as "2 buckets in this segment are outside your access" instead of their names, services or traffic. This is the same for buckets a rule adds.