---
title: Leads
subtitle: Leads are the most important object in Close.
---

Leads are the most important object in Close. They represent a company or organization and can contain contacts, tasks, opportunities, and activities. In fact, these other objects _must_ be children of a Lead. You can think of a Lead in Close like both a "lead" and "account" in the terminology of some other CRMs.

When a lead is returned, its basic info as well as related tasks, opportunities, and custom fields are included. Activities are excluded and must be fetched separately via the [Activities](/api/resources/activities) endpoint.

Custom fields that have a value are returned as `custom.FIELD_ID`, where FIELD_ID is the ID of the custom field (see [Custom Fields](/api/resources/custom-fields) for more details). Note that using the `custom` field dict is deprecated, and the field will be removed from the API.

When using the `_fields` parameter, specify `custom` to show all custom fields. Alternatively, only return a subset of custom fields by specifying a comma-separated list of one or more `custom.FIELD_ID` identifiers.

Smart Fields are not included in the response by default. To include them:

- Fetch a specific Smart Field with `?_fields=smart_field_name,other_lead_field_names`
- Fetch all Lead fields and all Smart Fields with `?_fields=_all`

Smart fields are calculated fields, like number of emails on a lead. To speed up your integration, we recommend that you only use the `_all` flag to discover what Smart Fields are available and then use `?_fields=specific,set,of,fields` to return only the fields you need.

To easily find Leads that match specific conditions, use the [Advanced Filtering API](/api/resources/advanced-filtering).