Course navigation
Course IntroductionLesson 2 of 6

What is Claude?

Claude is Anthropic's assistant for writing, coding, and everyday questions. This lesson covers what it is, what it handles well, and how it differs from ChatGPT and Gemini.

The short version

Claude is a chat tool you use at claude.ai. You type what you need in normal English; Claude replies with text you can copy, edit, or build on.

Anthropic released Claude in 2021. The company is known for long-document support and a direct writing style. You do not install anything to start — open the site, sign in, and send a message.

What happens when you send a message

Claude works from the text in your chat window. It has no access to your files, email, or desktop unless you add those through other Claude products covered later in this course.

Each message goes in, Claude produces a reply, and the thread continues from there. You do not need to know how the model is built — the same way you can use a search engine without knowing how it indexes the web.

  1. You type a message
  2. Claude returns a reply in the same chat
  3. You follow up, paste more context, or start a new chat

Two examples

Same interface for both — only the question changes.

Example 1 — plain-language question

claude.ai
Explain what inflation means in simple words.
C

Inflation is when prices rise over time.

If coffee cost ₹20 last year and ₹22 this year, your money buys a little less. Governments track inflation by watching the price of a fixed basket of everyday goods each month.

Example reply — inflation explained with a concrete number

Example 2 — code request

claude.ai
Write a Python function that checks if a number is prime.
C

A compact version that only tests divisors up to √n:

# Returns True if n is prime, False otherwise
def is_prime(n: int) -> bool:
if n < 2:
return False
for i in range(2, int(n**0.5) + 1):
if n % i == 0:
return False
return True
Example reply — function plus short note on the approach

What works well — and what does not

Claude handles well

  • Drafting and rewriting text
  • Explaining topics step by step
  • Reviewing and writing code
  • Summarising pasted documents
  • Translating between languages
  • Working through multi-step problems in chat

Limits to keep in mind

  • No live web access in basic chat (plugins add this)
  • No memory between separate chats
  • No direct access to your computer (Cowork does)
  • Can be wrong on facts — check important details
  • Not a substitute for medical, legal, or financial advice

Three model options

Pick a model in the chat settings. For most work in this course, Sonnet is the right default.

Haiku
Fastest replies
  • · Quick lookups
  • · Short rewrites
  • · High-volume chat
Sonnet
Default for daily use
  • · Writing and coding
  • · Longer threads
  • · Most lessons in this course
Opus
Heaviest lift
  • · Long reports
  • · Dense analysis
  • · When Sonnet falls short

Claude, ChatGPT, and Gemini

All three are capable. Differences matter when you pick a primary tool for a project.

TopicClaudeChatGPTGemini
CompanyAnthropicOpenAIGoogle
Strength called out oftenLong docs, careful prosePlugins and tool ecosystemTies to Google apps
Free tierYesYesYes
This courseWhat we teachMentioned for contextMentioned for context
We focus on Claude because the rest of this course — Chat, Code, Skills, Plugins, and Cowork — all build on it.

Before you continue

  • Claude lives at claude.ai; you only need a browser and an account.
  • Start with Sonnet unless you have a reason to switch.
  • Paste context, ask clearly, and verify anything high-stakes.
  • Next lesson: create your account and send your first message.

What's Next

Create your account and send your first message — about five minutes.

← PREVIOUS
Overview & Welcome
NEXT →
Getting Started