# login {#login}

**Parent topic:**[Functions](../../Functions/category.md)

## Syntax {#syntax}

`login(userId, password)`

## Arguments {#arguments}

**userId** a string indicating a user name. It can only contain letters, underscores, or numbers. It cannot start with numbers. The length cannot exceed 30 characters.

**password** a string indicating the password. It cannot contain space or control characters. The length must be between 6 and 20 characters.

## Details {#details}

A user logs in to operate on the controller or data nodes.

Since DolphinDB 2.00.10.10, users can determine whether to limit the number of failed login attempts by setting the configuration *enhancedSecurityVerification*. If it is not specified, no limit will be applied; if it is set to true, a user's account will be blocked for 10 minutes if the password is entered wrongly 5 times in a minute.

## Examples {#examples}

```
login(`JohnSmith, `Qb0507);
```

