# Data collection
Learn how to collect information for personalization.
This guide provides practical examples of using the Next.js SDK to enrich user profiles and sessions with information relevant to your business.
## User data
You can persist user-related information in one of the two ways described below depending on whether it is related to the user's profile or their current session.
### Profile data
You can enrich user profiles with details collected via forms, surveys, or other means.
These pieces of information, called *attributes*, are categorized as *standard* or *custom* depending on whether it is generic or specific to your organization.
#### Standard attributes
These are [predefined attributes](/reference/user/standard-attributes) that are common most businesses, such as the user's name, email, and interests.
You can set standard attributes using the [`user.edit`](/reference/sdk/javascript/api/user/edit) method. For example, let's say you have a newsletter subscription form, and you want to add the email address to the user profile on Croct.
This is what it would look like:
**Updating user profiles**
**JavaScript**
```jsx
import type {FormEvent} from 'react';
import {useCroct} from '@croct/plug-next';
export function NewsletterForm() {
const croct = useCroct();
const subscribe = event => {
const form = new FormData(event.currentTarget);
const email = form.get('email');
// Your logic to persist the email
api.subscribe(email);
croct.user.edit()
.set('email', email)
.save();
};
return (
);
}
```
**TypeScript**
```tsx
import type {FormEvent, ReactElement} from 'react';
import {useCroct} from '@croct/plug-next';
export function NewsletterForm(): ReactElement {
const croct = useCroct();
const subscribe = (event: FormEvent): void => {
const form = new FormData(event.currentTarget);
const email = String(form.get('email'));
// Your logic to persist the email
api.subscribe(email);
croct.user.edit()
.set('email', email)
.save();
};
return (
);
}
```
The [`user.edit`](/reference/sdk/javascript/api/user/edit) method returns a [`Patch`](/reference/sdk/javascript/api/patch) instance that allows you to chain multiple operations together.
You could alternatively write:
```tsx
const patch = croct.user.edit();
patch.set('email', email);
await patch.save();
```
When you call [`save`](/reference/sdk/javascript/api/patch/save), it saves changes to the user profile and returns a promise that confirms the operation.
You can then access standard attributes in your queries using the [`user`](/reference/cql/context#user) variable:
```cql
user's email ends with "@croct.com"
```
For a complete list of attributes, see [User profile reference](/reference/cql/data-types/user/user).
#### Custom attributes
In addition to the standard attributes, you can add [custom attributes](/reference/user/custom-attributes) to enrich user profiles with information relevant to your business.
For example, let's say you have a SaaS application and you want to ask your users about their area of expertise so you can personalize the onboarding experience.
This is what it would look like:
**JavaScript**
```jsx
import {useCroct} from '@croct/plug-next';
export function ExpertiseSelector() {
const croct = useCroct();
const onChange = event => {
croct.user.edit()
.set('custom.expertise', event.target.value)
.save();
};
return (
);
}
```
**TypeScript**
```tsx
import type {ReactElement, ChangeEvent} from 'react';
import {useCroct} from '@croct/plug-next';
export function ExpertiseSelector(): ReactElement {
const croct = useCroct();
const onChange = (event: ChangeEvent): void => {
croct.user.edit()
.set('custom.expertise', event.target.value)
.save();
};
return (
);
}
```
Note that custom attributes are prefixed with `custom` to avoid conflicts with standard attributes. However, you do not need to include the prefix in your queries:
```cql
user's expertise is "Engineering"
```
### Session data
Besides user profiles, you can also store information relevant to the user's current session.
Storing session information can help you keep track of important the user's current session that may not be relevant to their profile. For example, you can store the plan the user selected on the pricing page, or any other information you want to record during the user's visit.
To store session information, use the [`session.edit`](/reference/sdk/javascript/api/session/edit) method:
**Saving session data**
**JavaScript**
```jsx
import {useCroct} from '@croct/plug-next';
export function PlanCard({plan, price}) {
const croct = useCroct();
const onSelect = () => {
croct.session.edit()
.set('plan', plan)
.save();
};
return (