Suggest an editImprove this articleRefine the answer for “What does the OSI presentation layer do?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**The presentation layer (Presentation Layer)** is responsible for making sure data transmitted between applications is **understandable to both sides**. It handles *formatting, conversion, encryption, and compression of data*. **Key point:** the presentation layer converts data into a format suitable for transmission or processing: it encodes, decodes, encrypts, decrypts, and performs compression.Shown above the full answer for quick recall.Answer (EN)Image**The presentation layer (Presentation Layer)** is responsible for making sure data transmitted between applications is **understandable to both sides**. It handles *formatting, conversion, encryption, and compression of data*. Short formulation for an interview: > **The presentation layer converts data into a format suitable for transmission or processing: it encodes, decodes, encrypts, decrypts, and performs compression.** It is like a "translator" between the application and the network. --- ## Main functions of the presentation layer (L6) ### 1. Encoding and decoding data Layer 6 converts data into a standard format. Examples: - converting text to ASCII or UTF-8 - working with Unicode - converting data structures --- ### 2. Serialization and deserialization If the data is complex (for example, objects), L6 can: - **serialize** it: turn it into a byte stream - **deserialize** it: restore it upon receipt Examples: - JSON - XML - protobuf - ASN.1 --- ### 3. Encryption and decryption Cryptographic functions are often performed at the presentation layer. Examples: - SSL/TLS (partially assigned to L6 or L7, depending on the model) - TLS certificates - Base64 encoding --- ### 4. Compression and decompression of data To reduce the size of the transmitted information, layer 6 can perform: - zlib - gzip - JPEG/PNG for images - MP3/AAC for audio --- ### 5. Format conversion If two systems use different data formats, layer 6 provides the conversion. Examples: - little endian ↔ big endian - structured data → network format - data type conversion --- ## A simple analogy The presentation layer is a **translator + packer**: - translates data into a language both parties understand - encrypts a letter before sending it and decrypts it upon receipt - compresses data so it can be transmitted faster --- ## What the presentation layer does NOT do It's important not to confuse its tasks: The presentation layer does **not**: - establish sessions (that is layer 5) - transmit data between computers (layers 4-3) - work with frames or MAC (layer 2) - work with physical signals (layer 1) It deals with the *data format*, not its delivery. --- ## Examples of presentation layer technologies and protocols Although L6 is rarely singled out explicitly, it includes: - **SSL/TLS** (partially) - **Base64** - **ASCII/UTF-8/Unicode** - **JSON, XML, YAML** - **MIME types** - **ASN.1** (in certificates) - **gRPC and protobuf (partially)** --- ## A ready answer for an interview > **The OSI presentation layer handles converting data into a unified format: encoding, decoding, encryption, decryption, compression, and converting data structures.** > **It guarantees that data sent by an application on one device will be in the correct format, understandable to the application on another.** --- ## Cheat sheet (5 seconds) - L6 = **data format** - Encoding/decoding - Encryption/decryption - Compression/decompression - Converting structures and data types - A "translator" between the application and the networkFor the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.