Simple Chatbot in Python

What we are building

A chatbot talks with the user by reading their messages and replying. The easiest kind is a rule-based chatbot: it looks for keywords and gives a matching answer. It does not learn, but it teaches loops, conditions and string handling — and it is genuinely fun to build.

The chat loop

while True:
    msg = input("You: ").lower()
    if msg == "bye":
        print("Bot: Goodbye!")
        break
    print("Bot: I heard you say", msg)

A while True loop keeps the conversation going. We lowercase the input so matching is reliable, and break ends the chat when the user types "bye".

Keyword rules

while True:
    msg = input("You: ").lower()
    if "hello" in msg or "hi" in msg:
        print("Bot: Hello there!")
    elif "name" in msg:
        print("Bot: I am CodeBot.")
    elif "bye" in msg:
        print("Bot: Bye!")
        break
    else:
        print("Bot: Sorry, I did not understand.")

We check if keywords like "hello" or "name" appear in the message with in, and reply accordingly. The else handles anything we do not recognise.

Using a dictionary of replies

As rules grow, a dictionary keeps them tidy.

replies = {
    "hello": "Hi there!",
    "name": "I am CodeBot.",
    "help": "Ask me about Python!"
}

msg = input("You: ").lower()
answer = "Sorry, I did not understand."
for keyword in replies:
    if keyword in msg:
        answer = replies[keyword]
        break
print("Bot:", answer)

The dictionary maps each keyword to a reply. We loop over the keywords, and if one appears in the message, we use its reply. Adding a new rule is just one more dictionary entry.

Making it smarter

• More keywords. Add entries for common questions and greetings.
• Multiple matches. Handle messages that contain several keywords.
• Random replies. Store a list of answers per keyword and pick one at random.
• Go further. Later you can use NLP libraries or an AI model for real understanding.

Common mistakes

• Not lowercasing input. "Hello" would not match "hello" — use .lower().
• Using == instead of in. in checks if a keyword appears anywhere in the message.
• No exit condition. Without a "bye" break, the loop runs forever.
• No else fallback. Always handle messages you do not recognise.

Summary

• A rule-based chatbot replies to keywords in the message.
• A while True loop keeps the conversation going.
• Lowercase input and use in to match keywords.
• A dictionary of keyword-to-reply keeps many rules tidy.
• Always add an else fallback and a way to exit.

Next, strengthen the logic with Python loops, or organise replies with dictionaries.