diff --git a/Cargo.toml b/Cargo.toml
index 6913685..60eaac8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,13 @@ name = "rustmap"
 version = "0.1.0"
 authors = ["David Sommerich <d.j.s.1050@gmail.com>"]
 edition = "2018"
+description = "A very simple \"Nmap-like\" program that can scan for hosts and open TCP ports."
+readme = "README.md"
+homepage = "https://github.com/sommd/rustmap#readme"
+repository = "https://github.com/sommd/rustmap"
+license = "Apache-2.0"
+keyworks = ["nmap", "networking", "scan"]
+categories = ["command-line-utilities", "network-programming"]
 
 [dependencies]
 libc = "0.2.68"
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e10265d
--- /dev/null
+++ b/README.md
@@ -0,0 +1,70 @@
+# rustmap
+
+Rustmap is a very simple "Nmap-like" program that can scan for hosts and open TCP ports. It is mostly written for educational purposes (I wanted to learn Rust, and learn a bit more about how Nmap works) so it's quite slow and doesn't have many features.
+
+## Examples
+
+Check if a single host is up:
+
+```sh
+sudo rustmap 127.0.0.1
+```
+
+Scan all TCP ports for a single host:
+
+```sh
+sudo rustmap 127.0.0.1 -p
+```
+
+Scan all TCP ports for multiple hosts:
+
+```sh
+sudo rustmap 127.0.0.1 ::1 -p
+```
+
+Scan for specific ports in an address range:
+
+```sh
+sudo rustmap 127.0.0.0/8 -p 22,80,443
+```
+
+## Usage
+
+```sh
+rustmap [OPTIONS] <addr-ranges>...
+```
+
+### Flags
+
+#### `-h, --help`
+
+Prints help information
+
+#### `-V, --version`
+
+Prints version information
+
+### Options
+
+#### `-p, --ports <ports>...`
+
+Probe ports for each host and optionally specify which ports.
+
+Ports can be specified as a comma-separated list, or left unspecified to scan all ports.
+
+#### `-t, --timeout <timeout>`
+
+Timeout for pinging each host and probing each port.
+
+Parsing is provided by the [parse_duration](https://crates.io/crates/parse_duration) crate and supports almost any notation. E.g. `1s`, `10 seconds`, `1 hour, 15 minutes, 12 seconds`, `10m32s112ms`. [default: `1s`]
+
+### Args
+
+#### `<addr-ranges>...`
+
+IP addresses to scan.
+
+Supports IPv4 notation (e.g. `127.0.0.1`), IPv6 notation (e.g. `::1`), IPv4-mapped IPv6 notation (e.g. `::ffff::1.1.1.1`) and CIDR notation (e.g. `192.168.0.0/16`, `fe80::/10`).
+
+## License
+[Apache 2.0](./LICENSE)
diff --git a/src/main.rs b/src/main.rs
index 0f30e07..6f2ab07 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -12,15 +12,35 @@ use std::time::Duration;
 use structopt::StructOpt;
 
 #[derive(Debug, StructOpt)]
-#[structopt(name = "rustmap", about = "Scan for hosts or open ports.")]
+#[structopt()]
+/// Scan for hosts and open ports.
+///
+/// Needs to be run as root, or with the CAP_NET_RAW capability on Linux.
+///
+/// EXAMPLES:{n}
+/// {n}rustmap 127.0.0.1                   Check if a single host is up.
+/// {n}rustmap 127.0.0.1 -p                Scan all TCP ports for a single host.
+/// {n}rustmap 127.0.0.1 ::1 -p            Scan all TCP ports for multiple hosts.
+/// {n}rustmap 127.0.0.0/8 -p 22,80,443    Scan for specific ports in an address range.
 struct Opt {
-    #[structopt(short = "p", long = "--ports")]
+    #[structopt(short, long, require_delimiter = true)]
+    /// Probe ports for each host and optionally specify which ports.
+    ///
+    /// Ports can be specified as a comma-separated list, or left unspecified to scan all ports.
     ports: Option<Vec<u16>>,
 
     #[structopt(short, long, parse(try_from_str = parse_duration::parse), default_value = "1s")]
+    /// Timeout for pinging each host and probing each port.
+    ///
+    /// Parsing is provided by the 'parse_duration' crate and supports almost any notation.
+    /// E.g. '1s', '10 seconds', '1 hour, 15 minutes, 12 seconds', '10m32s112ms'.
     timeout: Duration,
 
     #[structopt(required = true)]
+    /// IP addresses to scan.
+    ///
+    /// Supports IPv4 notation (e.g. '127.0.0.1'), IPv6 notation (e.g. '::1'), IPv4-mapped IPv6
+    /// notation (e.g. '::ffff::1.1.1.1') and CIDR notation (e.g. '192.168.0.0/16', 'fe80::/10').
     addr_ranges: Vec<IpAddrRange>,
 }