diff --git a/Cargo.lock b/Cargo.lock
index a2453031e..549eae40b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1992,11 +1992,13 @@ dependencies = [
 name = "r3bl_rs_utils_core"
 version = "0.9.16"
 dependencies = [
+ "assert_cmd",
  "chrono",
  "colorgrad",
  "crossterm 0.28.1",
  "futures-util",
  "log",
+ "miette",
  "nom",
  "pretty_assertions",
  "r3bl_ansi_color",
@@ -2008,6 +2010,8 @@ dependencies = [
  "sha2",
  "size-of",
  "strip-ansi",
+ "tempfile",
+ "thiserror",
  "time",
  "tokio",
  "tracing",
@@ -2044,7 +2048,6 @@ dependencies = [
 name = "r3bl_terminal_async"
 version = "0.5.7"
 dependencies = [
- "assert_cmd",
  "async-stream",
  "crossterm 0.28.1",
  "futures-core",
@@ -2061,7 +2064,6 @@ dependencies = [
  "r3bl_tuify",
  "strum",
  "strum_macros",
- "tempfile",
  "thiserror",
  "tokio",
  "tracing",
diff --git a/core/Cargo.toml b/core/Cargo.toml
index b95165ade..b665b49d4 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -70,7 +70,21 @@ futures-util = "0.3.30"                                         # Needed for cro
 # Color gradients.
 colorgrad = "0.7.0"
 
+# Error handling.
+thiserror = "1.0.63"
+miette = { version = "7.2.0", features = ["fancy"] }
+pretty_assertions = "1.4.0"
+
 [dev-dependencies]
 # for assert_eq! macro
 pretty_assertions = "1.4.0"
-serial_test = "3.1.1"
\ No newline at end of file
+serial_test = "3.1.1"
+
+# Testing - temp files and folders.
+tempfile = "3.12.0"
+
+# Bin targets for testing stdout and stderr.
+assert_cmd = "2.0.16"
+[[bin]]
+name = "tracing_test_bin"
+path = "src/bin/tracing_test_bin.rs"
diff --git a/terminal_async/src/bin/tracing_test_bin.rs b/core/src/bin/tracing_test_bin.rs
similarity index 94%
rename from terminal_async/src/bin/tracing_test_bin.rs
rename to core/src/bin/tracing_test_bin.rs
index 34c5c0966..07f49f05b 100644
--- a/terminal_async/src/bin/tracing_test_bin.rs
+++ b/core/src/bin/tracing_test_bin.rs
@@ -15,7 +15,7 @@
  *   limitations under the License.
  */
 
-use r3bl_terminal_async::{init_tracing, DisplayPreference, TracingConfig, WriterConfig};
+use r3bl_rs_utils_core::{init_tracing, DisplayPreference, TracingConfig, WriterConfig};
 
 /// `assert_cmd` : <https://docs.rs/assert_cmd/latest/assert_cmd/index.html>
 ///
diff --git a/core/src/lib.rs b/core/src/lib.rs
index 7ae21ed58..599a7877d 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -132,6 +132,7 @@ pub mod decl_macros;
 pub mod logging;
 pub mod misc;
 pub mod terminal_io;
+pub mod tracing_logging;
 pub mod tui_core;
 
 // Re-export.
@@ -140,4 +141,5 @@ pub use decl_macros::*;
 pub use logging::*;
 pub use misc::*;
 pub use terminal_io::*;
+pub use tracing_logging::*;
 pub use tui_core::*;
diff --git a/terminal_async/src/tracing_logging/init_tracing.rs b/core/src/tracing_logging/init_tracing.rs
similarity index 94%
rename from terminal_async/src/tracing_logging/init_tracing.rs
rename to core/src/tracing_logging/init_tracing.rs
index 2723c1ff7..554036af0 100644
--- a/terminal_async/src/tracing_logging/init_tracing.rs
+++ b/core/src/tracing_logging/init_tracing.rs
@@ -15,6 +15,16 @@
  *   limitations under the License.
  */
 
+//! # [init_tracing]
+//!
+//! This is a convenience method to setup Tokio [`tracing_subscriber`] with `stdout` as
+//! the output destination. This method also ensures that the [`crate::SharedWriter`] is
+//! used for concurrent writes to `stdout`. You can also use the [`TracingConfig`] struct
+//! to customize the behavior of the tracing setup, by choosing whether to display output
+//! to `stdout`, `stderr`, or a [`crate::SharedWriter`]. By default, both display and file
+//! logging are enabled. You can also customize the log level, and the file path and
+//! prefix for the log file.
+
 use tracing_core::LevelFilter;
 use tracing_subscriber::{layer::SubscriberExt,
                          registry::LookupSpan,
@@ -258,9 +268,8 @@ mod test_tracing_bin_stdio {
 
 #[cfg(test)]
 mod test_tracing_shared_writer_output {
-    use r3bl_rs_utils_core::{LineStateControlSignal, SharedWriter};
-
     use super::*;
+    use crate::{LineStateControlSignal, SharedWriter};
 
     const EXPECTED: [&str; 4] = ["error", "warn", "info", "debug"];
 
diff --git a/terminal_async/src/tracing_logging/mod.rs b/core/src/tracing_logging/mod.rs
similarity index 100%
rename from terminal_async/src/tracing_logging/mod.rs
rename to core/src/tracing_logging/mod.rs
diff --git a/terminal_async/src/tracing_logging/rolling_file_appender_impl.rs b/core/src/tracing_logging/rolling_file_appender_impl.rs
similarity index 100%
rename from terminal_async/src/tracing_logging/rolling_file_appender_impl.rs
rename to core/src/tracing_logging/rolling_file_appender_impl.rs
diff --git a/terminal_async/src/tracing_logging/tracing_config.rs b/core/src/tracing_logging/tracing_config.rs
similarity index 98%
rename from terminal_async/src/tracing_logging/tracing_config.rs
rename to core/src/tracing_logging/tracing_config.rs
index a3840f100..07075cc8c 100644
--- a/terminal_async/src/tracing_logging/tracing_config.rs
+++ b/core/src/tracing_logging/tracing_config.rs
@@ -17,9 +17,10 @@
 
 use std::fmt::Debug;
 
-use r3bl_rs_utils_core::SharedWriter;
 use tracing_core::LevelFilter;
 
+use crate::SharedWriter;
+
 /// Configure the tracing logging to suit your needs. You can display the logs to a:
 /// 1. file,
 /// 2. stdout, stderr, or a shared writer,
diff --git a/terminal_async/Cargo.toml b/terminal_async/Cargo.toml
index 44b80134f..4c48ba3a8 100644
--- a/terminal_async/Cargo.toml
+++ b/terminal_async/Cargo.toml
@@ -78,15 +78,6 @@ async-stream = "0.3.5"
 # Testing - r3bl-open-core.
 r3bl_test_fixtures = { path = "../test_fixtures" }
 
-# Testing - temp files and folders.
-tempfile = "3.12.0"
-
-# Bin targets for testing stdout and stderr.
-assert_cmd = "2.0.16"
-[[bin]]
-name = "tracing_test_bin"
-path = "src/bin/tracing_test_bin.rs"
-
 [features]
 default = ["emacs"]
 emacs = []
diff --git a/terminal_async/README.md b/terminal_async/README.md
index 78eef9078..18897335d 100644
--- a/terminal_async/README.md
+++ b/terminal_async/README.md
@@ -103,7 +103,6 @@ niceties & ergonomics that all Rustaceans 🦀 can enjoy 🎉.
   - [Readline overview please see the docs for this struct for
     details](#readline-overview-please-see-the-docs-for-this-struct-for-details)
   - [Spinner::try_start](#spinnertry_start)
-  - [init_tracing()](#init_tracing)
 - [Build this crate with Naz on YouTube](#build-this-crate-with-naz-on-youtube)
 - [Why another async readline crate?](#why-another-async-readline-crate)
   - [References for blocking and thread cancellation in
@@ -365,17 +364,6 @@ have ANSI escape sequences in them. Here's an example of this.
     Ok(())
 ```
 
-### [`init_tracing()`]
-
-This is a convenience method to setup Tokio [`tracing_subscriber`] with `stdout` as
-the output destination. This method also ensures that the
-[`r3bl_rs_utils_core::SharedWriter`] is used for concurrent writes to `stdout`. You
-can also use the [`TracingConfig`] struct to customize the behavior of the tracing
-setup, by choosing whether to display output to `stdout`, `stderr`, or a
-[`r3bl_rs_utils_core::SharedWriter`]. By default, both display and file logging are
-enabled. You can also customize the log level, and the file path and prefix for the
-log file.
-
 ## Build this crate with Naz on YouTube
 
 Watch the following videos to learn more about how this crate was built:
diff --git a/terminal_async/examples/terminal_async.rs b/terminal_async/examples/terminal_async.rs
index a512976de..677b14288 100644
--- a/terminal_async/examples/terminal_async.rs
+++ b/terminal_async/examples/terminal_async.rs
@@ -22,10 +22,10 @@ use std::{io::{stderr, Write},
 
 use crossterm::style::Stylize;
 use miette::IntoDiagnostic;
-use r3bl_rs_utils_core::SharedWriter;
-use r3bl_terminal_async::{tracing_logging::tracing_config::TracingConfig,
-                          DisplayPreference,
-                          Readline,
+use r3bl_rs_utils_core::{tracing_logging::tracing_config::TracingConfig,
+                         DisplayPreference,
+                         SharedWriter};
+use r3bl_terminal_async::{Readline,
                           ReadlineEvent,
                           Spinner,
                           SpinnerStyle,
@@ -152,7 +152,7 @@ async fn main() -> miette::Result<()> {
     }
 
     // Initialize tracing w/ the "async stdout" (SharedWriter), and file writer.
-    r3bl_terminal_async::init_tracing(TracingConfig::new_file_and_display(
+    r3bl_rs_utils_core::init_tracing(TracingConfig::new_file_and_display(
         None,
         DisplayPreference::SharedWriter(terminal_async.clone_shared_writer()),
     ))?;
diff --git a/terminal_async/src/lib.rs b/terminal_async/src/lib.rs
index c54fc0bca..6276082ec 100644
--- a/terminal_async/src/lib.rs
+++ b/terminal_async/src/lib.rs
@@ -118,7 +118,6 @@
 //!   - [Readline overview please see the docs for this struct for
 //!     details](#readline-overview-please-see-the-docs-for-this-struct-for-details)
 //!   - [Spinner::try_start](#spinnertry_start)
-//!   - [init_tracing()](#init_tracing)
 //! - [Build this crate with Naz on YouTube](#build-this-crate-with-naz-on-youtube)
 //! - [Why another async readline crate?](#why-another-async-readline-crate)
 //!   - [References for blocking and thread cancellation in
@@ -384,17 +383,6 @@
 //! # }
 //! ```
 //!
-//! ## [`init_tracing()`]
-//!
-//! This is a convenience method to setup Tokio [`tracing_subscriber`] with `stdout` as
-//! the output destination. This method also ensures that the
-//! [`r3bl_rs_utils_core::SharedWriter`] is used for concurrent writes to `stdout`. You
-//! can also use the [`TracingConfig`] struct to customize the behavior of the tracing
-//! setup, by choosing whether to display output to `stdout`, `stderr`, or a
-//! [`r3bl_rs_utils_core::SharedWriter`]. By default, both display and file logging are
-//! enabled. You can also customize the log level, and the file path and prefix for the
-//! log file.
-//!
 //! # Build this crate with Naz on YouTube
 //!
 //! Watch the following videos to learn more about how this crate was built:
@@ -471,14 +459,12 @@ pub mod public_api;
 pub mod readline_impl;
 pub mod spinner_impl;
 pub mod tracing_jaeger;
-pub mod tracing_logging;
 
 // Re-export the public API.
 pub use public_api::*;
 pub use readline_impl::*;
 pub use spinner_impl::*;
 pub use tracing_jaeger::*;
-pub use tracing_logging::*;
 
 // External crates.
 use std::{collections::VecDeque, io::Error, pin::Pin, sync::Arc};
diff --git a/tui/README.md b/tui/README.md
index 342541bd6..baa03583c 100644
--- a/tui/README.md
+++ b/tui/README.md
@@ -877,15 +877,15 @@ let st = lolcat_mut.colorize_to_styled_texts(&unicode_string);
 lolcat.next_color();
 ```
 
-This [crate::Lolcat] that is returned by `build()` is safe to re-use.
+This [r3bl_rs_utils_core::Lolcat] that is returned by `build()` is safe to re-use.
 - The colors it cycles through are "stable" meaning that once constructed via the
-  [builder](crate::LolcatBuilder) (which sets the speed, seed, and delta that
-  determine where the color wheel starts when it is used). For eg, when used in a
+  [builder](r3bl_rs_utils_core::LolcatBuilder) (which sets the speed, seed, and delta
+  that determine where the color wheel starts when it is used). For eg, when used in a
   dialog box component that re-uses the instance, repeated calls to the `render()`
   function of this component will produce the same generated colors over and over
   again.
 - If you want to change where the color wheel "begins", you have to change the speed,
-  seed, and delta of this [crate::Lolcat] instance.
+  seed, and delta of this [r3bl_rs_utils_core::Lolcat] instance.
 
 ## Issues and PRs
 
diff --git a/tui/src/lib.rs b/tui/src/lib.rs
index fe5d23474..63c5ebf3f 100644
--- a/tui/src/lib.rs
+++ b/tui/src/lib.rs
@@ -892,15 +892,15 @@
 //! lolcat.next_color();
 //! ```
 //!
-//! This [crate::Lolcat] that is returned by `build()` is safe to re-use.
+//! This [r3bl_rs_utils_core::Lolcat] that is returned by `build()` is safe to re-use.
 //! - The colors it cycles through are "stable" meaning that once constructed via the
-//!   [builder](crate::LolcatBuilder) (which sets the speed, seed, and delta that
-//!   determine where the color wheel starts when it is used). For eg, when used in a
+//!   [builder](r3bl_rs_utils_core::LolcatBuilder) (which sets the speed, seed, and delta
+//!   that determine where the color wheel starts when it is used). For eg, when used in a
 //!   dialog box component that re-uses the instance, repeated calls to the `render()`
 //!   function of this component will produce the same generated colors over and over
 //!   again.
 //! - If you want to change where the color wheel "begins", you have to change the speed,
-//!   seed, and delta of this [crate::Lolcat] instance.
+//!   seed, and delta of this [r3bl_rs_utils_core::Lolcat] instance.
 //!
 //! # Issues and PRs
 //!
diff --git a/tui/src/tui/layout/props.rs b/tui/src/tui/layout/props.rs
index beb222ab3..03230cdd1 100644
--- a/tui/src/tui/layout/props.rs
+++ b/tui/src/tui/layout/props.rs
@@ -19,7 +19,7 @@ use r3bl_rs_utils_core::{Position, RequestedSizePercent, Size, TuiStyle};
 
 use super::{FlexBoxId, LayoutDirection};
 
-/// Properties that are needed to create a [FlexBox].
+/// Properties that are needed to create a [crate::FlexBox].
 #[derive(Clone, Debug, Default)]
 pub struct FlexBoxProps {
     pub id: FlexBoxId,
diff --git a/tui/src/tui/syntax_highlighting/md_parser_syn_hi/md_parser_syn_hi_impl.rs b/tui/src/tui/syntax_highlighting/md_parser_syn_hi/md_parser_syn_hi_impl.rs
index f7dd3aeba..431289c05 100644
--- a/tui/src/tui/syntax_highlighting/md_parser_syn_hi/md_parser_syn_hi_impl.rs
+++ b/tui/src/tui/syntax_highlighting/md_parser_syn_hi/md_parser_syn_hi_impl.rs
@@ -78,10 +78,10 @@ use crate::{constants::{AUTHORS,
             StyleUSSpanLines,
             US};
 
-/// This is the main function that the [editor] uses this in order to display the markdown to the
-/// user.It is responsible for converting:
-/// - from a &[Vec] of [US] which comes from the [editor],
-/// - into a [StyleUSSpanLines], which the [editor] will clip & render.
+/// This is the main function that the [crate::editor] uses this in order to display the
+/// markdown to the user.It is responsible for converting:
+/// - from a &[Vec] of [US] which comes from the [crate::editor],
+/// - into a [StyleUSSpanLines], which the [crate::editor] will clip & render.
 ///
 /// # Arguments
 /// - `editor_text` - The text that the user has typed into the editor.
diff --git a/tui/src/tui/terminal_lib_backends/z_order.rs b/tui/src/tui/terminal_lib_backends/z_order.rs
index e1fa0f6bf..287732cee 100644
--- a/tui/src/tui/terminal_lib_backends/z_order.rs
+++ b/tui/src/tui/terminal_lib_backends/z_order.rs
@@ -27,7 +27,8 @@ pub enum ZOrder {
 }
 
 impl ZOrder {
-    /// Contains the priority that is used to paint the different groups of [RenderOp] items.
+    /// Contains the priority that is used to paint the different groups of
+    /// [crate::RenderOp] items.
     pub fn get_render_order() -> [ZOrder; 3] {
         [ZOrder::Normal, ZOrder::High, ZOrder::Glass]
     }