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+# Simple Multithreaded TCP Counter Server
+
+This project implements a basic multithreaded TCP server in C that maintains a
+shared integer counter. Clients can connect to the server and send commands to
+modify or query the counter value concurrently.
+
+## Features
+
+- Handles multiple clients concurrently using POSIX threads (`pthread`).
+- Synchronizes access to a shared counter variable with a mutex to avoid race conditions.
+- Supports three commands from clients:
+    - `up` — increments the counter by 1.
+    - `down` — decrements the counter by 1.
+    - `show` — returns the current value of the counter.
+- Responds with `"Ok\n"` to confirm `up` and `down` commands.
+- Responds with the counter value followed by newline for `show` command.
+- Handles unknown commands gracefully with an error message.
+- Uses semaphores for thread synchronization on startup.
+- Detaches threads after creation to clean up resources automatically.
+
+## How It Works
+
+- The server listens on a TCP port specified as a command-line argument.
+- For each incoming client connection, it spawns a detached worker thread.
+- The worker thread reads commands line-by-line from the client socket.
+- Commands are parsed and processed with proper mutex locking on the shared counter.
+- The connection closes when the client disconnects.
+
+## Usage
+
+Build with:
+
+```bash
+git clone https://git.scratko.xyz/threaded-tcp-counter
+gcc -pthread -o tcp_counter_server server.c
+```
+Run:
+
+```bash
+./tcp_counter_server <port>
+```
+
+Example:
+```bash
+./tcp_counter_server 12345
+```
+Then connect with telnet or netcat:
+```bash
+telnet localhost 12345
+```
+Send commands like:
+
+```bash
+up
+show
+down
+show
+```
+
+## Limitations and Notes
+
+- The server currently uses a single shared `thread_data` struct, which may
+  cause race conditions if multiple clients connect simultaneously. Improvements
+  could include per-thread data allocation.
+- The server supports only simple line-based commands.
+- No security or authentication.
+- Minimal error handling for simplicity.
+