Python Web Scraper Project: Step-by-Step Code & Tutorial

### Step 1: Project Setup Create folder `web_scraper` and script `scraper.py`. We use `urllib.request` and `csv`.

### Step 2: Core Logic Implementation Implement the HTML fetching function with custom User-Agent headers to ensure polite requests. ```python import urllib.request import urllib.error import re import csv def fetch_html(url: string) -> string: req = urllib.request.Request( url, headers={'User-Agent': 'Mozilla/5.0 (Education Bot)'} ) with urllib.request.urlopen(req) as response: return response.read().decode('utf-8') ```

### Step 3: Parsing & Exporting Extract headlines and write to CSV. ```python def parse_headlines(html: string) -> list: # Extracting standard h2 tags using regex for demonstration matches = re.findall(r'

(.*?)<\/h2>', html, re.DOTALL) clean = [re.sub(r'<.*?>', '', m).strip() for m in matches] return clean ```

### Step 4: Politeness & Exceptions Always catch HTTP errors (404, 500) and respect crawl delays.