App = Flask( name )

django.forms class, such as CharField or EmailField. We can then use this form in our views to process user input.

3. 
   WTForms: WTForms is a popular forms library for Python that can be used with many different web frameworks. WTForms provides a simple syntax for defining forms and validating user input. Here's an example:
   

from wtforms import Form, StringField, TextAreaField, validators

class ContactForm(Form):

name = StringField('Name', [validators.Length(min=2, max=100)])
email = StringField('Email', [validators.Email()])
message = TextAreaField('Message', [validators.Length(min=10)])
In this example, we define a form that includes fields for name, email, and message. Each field is defined as an instance of a wtforms class, such as StringField or TextAreaField. We also define validation rules for each field using the validators module. We can then use this form in our views to process user input.

4. 
   Pydantic: Pydantic is a data validation library for Python that can be used to validate user input in many different contexts, including forms. Pydantic uses Python type annotations to define data models and validation rules. Here's an example:
   

from pydantic import BaseModel, validator

class ContactForm(BaseModel):

name: str
email: str
message: str

@validator('name')

def name_length(cls, v):
VALIDATION

Validation is the process of checking whether the data entered by the user or received from another source is valid or not. In Python, validation can be performed in several ways, depending on the application architecture and requirements. Here are some of the most common methods:

1. 
   Built-in Python data types: Python provides built-in data types such as str, int, float, and bool that can be used to validate user input. For example, to check whether a user input is a valid integer, you can use the