diff --git a/README.md b/README.md
index f3a04bc..0837adc 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ simple and easy to use.
   - MOV
   - MP4
 
-## Sync API usage
+## Sync API Usage
 
 ```rust
 use nom_exif::*;
@@ -68,7 +68,6 @@ fn main() -> Result<()> {
     // You can also iterate it in a `for` loop. Clone it first so we won't
     // consume the original one. Note that the new cloned `ExifIter` will
     // always start from the first entry.
-
     for entry in iter.clone() {
         if entry.tag().unwrap() == ExifTag::Make {
             assert_eq!(entry.take_result()?.as_str().unwrap(), "Apple");
@@ -88,11 +87,7 @@ fn main() -> Result<()> {
         res.join(", "),
         "Make(0x010f) => Apple, Model(0x0110) => iPhone 12 Pro"
     );
-
-    // `ExifIter` provides a convenience method for parsing gps information
-    let gps_info = iter.parse_gps_info().unwrap().unwrap();
-    assert_eq!(gps_info.format_iso6709(), "+43.29013+084.22713+1595.950/");
-
+    
     // An `ExifIter` can be easily converted to an `Exif`
     let exif: Exif = iter.into();
     assert_eq!(
@@ -103,8 +98,19 @@ fn main() -> Result<()> {
 }
 ```
 
-## Async API usage
+## Async API Usage
+
+Enable `async` feature flag for nom-exif in your `Cargo.toml`:
 
+```toml
+[dependencies]
+nom-exif = { version = "1", features = ["async"] }
+```
+
+Since parsing process is a CPU-bound task, you may want to move the job to
+a separated thread (better to use rayon crate). There is a simple example
+below.
+    
 You can safely and cheaply clone an [`ExifIter`] in multiple tasks/threads
 concurrently, since it use `Arc` to share the underlying memory.
 
@@ -127,9 +133,6 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         }
     }
 
-    // Since parsing process is a CPU-bound task, we can move the job to a
-    // separated thread (better to use rayon crate).
-
     // Convert an `ExifIter` into an `Exif` in a separated thread.
     let exif = spawn_blocking(move || {
         let exif: Exif = iter.into();
@@ -147,6 +150,25 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 fn main() {}
 ```
 
+## GPS Info
+
+`ExifIter` provides a convenience method for parsing gps information.
+(`Exif` also provides a `get_gps_info` mthod).
+    
+```rust
+use nom_exif::*;
+use std::fs::File;
+
+fn main() -> Result<()> {
+    let f = File::open("./testdata/exif.heic")?;
+    let iter = parse_exif(f, None)?.unwrap();
+
+    let gps_info = iter.parse_gps_info()?.unwrap();
+    assert_eq!(gps_info.format_iso6709(), "+43.29013+084.22713+1595.950/");
+    Ok(())
+}
+```
+
 For more usage details, please refer to the [API
 documentation](https://docs.rs/nom-exif/latest/nom_exif/).
 
diff --git a/src/lib.rs b/src/lib.rs
index 3538c9c..923dc83 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -41,7 +41,7 @@
 //!   - MOV
 //!   - MP4
 //!
-//! ## Sync API usage
+//! ## Sync API Usage
 //!
 //! ```rust
 //! use nom_exif::*;
@@ -61,7 +61,6 @@
 //!     // You can also iterate it in a `for` loop. Clone it first so we won't
 //!     // consume the original one. Note that the new cloned `ExifIter` will
 //!     // always start from the first entry.
-//!
 //!     for entry in iter.clone() {
 //!         if entry.tag().unwrap() == ExifTag::Make {
 //!             assert_eq!(entry.take_result()?.as_str().unwrap(), "Apple");
@@ -81,11 +80,7 @@
 //!         res.join(", "),
 //!         "Make(0x010f) => Apple, Model(0x0110) => iPhone 12 Pro"
 //!     );
-//!
-//!     // `ExifIter` provides a convenience method for parsing gps information
-//!     let gps_info = iter.parse_gps_info().unwrap().unwrap();
-//!     assert_eq!(gps_info.format_iso6709(), "+43.29013+084.22713+1595.950/");
-//!
+//!     
 //!     // An `ExifIter` can be easily converted to an `Exif`
 //!     let exif: Exif = iter.into();
 //!     assert_eq!(
@@ -96,8 +91,19 @@
 //! }
 //! ```
 //!
-//! ## Async API usage
+//! ## Async API Usage
+//!
+//! Enable `async` feature flag for nom-exif in your `Cargo.toml`:
 //!
+//! ```toml
+//! [dependencies]
+//! nom-exif = { version = "1", features = ["async"] }
+//! ```
+//!
+//! Since parsing process is a CPU-bound task, you may want to move the job to
+//! a separated thread (better to use rayon crate). There is a simple example
+//! below.
+//!     
 //! You can safely and cheaply clone an [`ExifIter`] in multiple tasks/threads
 //! concurrently, since it use `Arc` to share the underlying memory.
 //!
@@ -120,9 +126,6 @@
 //!         }
 //!     }
 //!
-//!     // Since parsing process is a CPU-bound task, we can move the job to a
-//!     // separated thread (better to use rayon crate).
-//!
 //!     // Convert an `ExifIter` into an `Exif` in a separated thread.
 //!     let exif = spawn_blocking(move || {
 //!         let exif: Exif = iter.into();
@@ -140,6 +143,25 @@
 //! fn main() {}
 //! ```
 //!
+//! ## GPS Info
+//!
+//! `ExifIter` provides a convenience method for parsing gps information.
+//! (`Exif` also provides a `get_gps_info` mthod).
+//!     
+//! ```rust
+//! use nom_exif::*;
+//! use std::fs::File;
+//!
+//! fn main() -> Result<()> {
+//!     let f = File::open("./testdata/exif.heic")?;
+//!     let iter = parse_exif(f, None)?.unwrap();
+//!
+//!     let gps_info = iter.parse_gps_info()?.unwrap();
+//!     assert_eq!(gps_info.format_iso6709(), "+43.29013+084.22713+1595.950/");
+//!     Ok(())
+//! }
+//! ```
+//!
 //! For more usage details, please refer to the [API
 //! documentation](https://docs.rs/nom-exif/latest/nom_exif/).