# Typical User Registration Workflow

A guide to the standard steps involved in registering a new user on a web application.

## Overview

User registration is one of the most fundamental features of any application. It involves collecting user information, validating it, and creating a new account. Below is the high-level flow.

```mermaid
flowchart TD
    A[User visits registration page] --> B[Fill in registration form]
    B --> C{Client-side validation}
    C -->|Invalid| D[Show error messages]
    D --> B
    C -->|Valid| E[Submit form to server]
    E --> F{Server-side validation}
    F -->|Invalid| G[Return validation errors]
    G --> B
    F -->|Valid| H{Check if user exists}
    H -->|Already exists| I[Return 'email taken' error]
    I --> B
    H -->|New user| J[Hash password]
    J --> K[Save user to database]
    K --> L[Send verification email]
    L --> M[Show success message]
```

## Detailed Steps

### 1. Registration Form

The user fills in a form with typical fields like name, email, and password. Here's what the form data flow looks like:

```mermaid
flowchart LR
    subgraph Form Fields
        A[Name]
        B[Email]
        C[Password]
        D[Confirm Password]
    end

    subgraph Validation Rules
        A --> E[Required, 2-50 chars]
        B --> F[Required, valid email format]
        C --> G[Min 8 chars, uppercase, number, symbol]
        D --> H[Must match password]
    end
```

### 2. Server-Side Processing

Once the form passes client-side checks, the server handles the heavy lifting:

```mermaid
sequenceDiagram
    participant U as User Browser
    participant S as Server
    participant DB as Database
    participant E as Email Service

    U->>S: POST /api/register (name, email, password)
    S->>S: Validate input & sanitize
    S->>DB: Check if email already exists
    DB-->>S: Result
    alt Email exists
        S-->>U: 409 Conflict - Email taken
    else New user
        S->>S: Hash password (bcrypt)
        S->>DB: Insert new user record
        DB-->>S: User created
        S->>S: Generate verification token
        S->>E: Send verification email
        E-->>S: Email sent
        S-->>U: 201 Created - Check your email
    end
```

### 3. Email Verification

After registration, the user needs to verify their email address:

```mermaid
flowchart TD
    A[User receives email] --> B[Clicks verification link]
    B --> C[Server receives token]
    C --> D{Token valid?}
    D -->|Expired| E[Show 'link expired' error]
    E --> F[Offer to resend email]
    D -->|Invalid| G[Show 'invalid link' error]
    D -->|Valid| H[Mark email as verified]
    H --> I[Redirect to login page]
    I --> J[User logs in for the first time]
```

### 4. User States

A registered user goes through several states:

```mermaid
stateDiagram-v2
    [*] --> Registered: Completes signup
    Registered --> Verified: Confirms email
    Registered --> Expired: Verification timeout
    Expired --> Registered: Resends verification
    Verified --> Active: First login
    Active --> Suspended: Policy violation
    Suspended --> Active: Account restored
    Active --> Deleted: Account deletion
    Deleted --> [*]
```

## Security Best Practices

When implementing user registration, keep these in mind: always hash passwords with a strong algorithm like bcrypt, use HTTPS for all form submissions, implement rate limiting to prevent brute-force attacks, add CAPTCHA for bot protection, and never store passwords in plain text.

## Summary

A well-designed registration flow balances security with user experience. The key stages are form input, validation (both client and server), account creation with password hashing, and email verification. Each step should provide clear feedback so the user always knows what's happening.