Hashing, encoding & encryption- When to use which ?

 If you’ve ever nodded along in a meeting pretending you totally know the difference between hashing, encoding, and encryption... Congrats — you’re officially a developer. 😅 But don’t worry, we’re about to clear it up. Forever. In English. No jargon. No judgment.

𝐇𝐚𝐬𝐡𝐢𝐧𝐠 :
Hashing is like a fingerprint for your data.
 Hashing creates a fixed-length digest from data — it's one-way and irreversible.
Even a tiny change gives a completely different hash. That’s why it is perfect for fingerprinting and integrity checks.

𝐄𝐧𝐜𝐨𝐝𝐢𝐧𝐠 :
Encoding transforms data into another format using a public algorithm, so it's fully reversible with no key. It does not require a key as the only thing required to decode it is the algorithm that was used to encode it.
The goal of encoding is format compatibility

𝐄𝐧𝐜𝐫𝐲𝐩𝐭𝐢𝐨𝐧
Encryption transforms data to a secret format that only someone with the correct key can decrypt.
The goal of encryption is data confidentiality

🧠 𝐓𝐋;𝐃𝐑

- Hashing = Integrity check 🔍
- Encoding = Format compatibility 🧾
- Encryption = Data confidentiality 🔐

𝐖𝐡𝐞𝐧 𝐭𝐨 𝐞𝐧𝐜𝐫𝐲𝐩𝐭 ?
Use encryption when you need to send or store sensitive data and retrieve it later.
eg: If you're sending sensitive stuff — like credit card data — encrypt it. That way, only the right person with the key can read it.
But, why not encode ? Because, encoding is easily reversible & insecure
Why not hash ? Because, You can’t get the original data back

𝐖𝐡𝐞𝐧 𝐭𝐨 𝐡𝐚𝐬𝐡?
When something is hashed, the created hash is often much smaller , so information gets lost .
Use hashing when you never need the original — just want to verify it hasn’t changed.

eg: When storing user passwords- we hash it . You only need to compare passwords, not retrieve them. That way a person/server can check if the hash of your password matches, without knowing your actual password.

Why not encode the passwords? Because, encoding is easily reversible & insecure.

Why not encrypt the passwords? Too much risk if the key is leaked , also unnecessary since you don’t need to decrypt.

𝐖𝐡𝐞𝐧 𝐭𝐨 𝐞𝐧𝐜𝐨𝐝𝐞?
Use encoding for format compatibility, not secrecy or verification.

eg: When we are sending binary files in a JSON API we use base64 Encoding

JSON is a text-based format , so it can't handle raw binary data like images or PDFs.
Encoding (like Base64) converts binary into text, making it safe to include in JSON payloads.

Why not Hashing?
Hashing gives you a fingerprint, not the original file. It's one-way, so you lose the data.

Why not Encryption?
Encryption keeps data secret ,but in this case, you just want it to be readable in JSON, not hidden.