* **Async Hooks**
  * The `async_hooks` module has landed in core
    [[`4a7233c178`](4a7233c178)]
    [#12892](#12892).

* **Buffer**
  * Using the `--pending-deprecation` flag will cause Node.js to emit a
    deprecation warning when using `new Buffer(num)` or `Buffer(num)`.
    [[`d2d32ea5a2`](d2d32ea5a2)]
    [#11968](#11968).
  * `new Buffer(num)` and `Buffer(num)` will zero-fill new `Buffer` instances
    [[`7eb1b4658e`](7eb1b4658e)]
    [#12141](#12141).
  * Many `Buffer` methods now accept `Uint8Array` as input
    [[`beca3244e2`](beca3244e2)]
    [#10236](#10236).

* **Child Process**
  * Argument and kill signal validations have been improved
    [[`97a77288ce`](97a77288ce)]
    [#12348](#12348),
    [[`d75fdd96aa`](d75fdd96aa)]
    [#10423](#10423).
  * Child Process methods accept `Uint8Array` as input
    [[`627ecee9ed`](627ecee9ed)]
    [#10653](#10653).

* **Console**
  * Error events emitted when using `console` methods are now supressed.
    [[`f18e08d820`](f18e08d820)]
    [#9744](#9744).

* **Dependencies**
  * The npm client has been updated to 5.0.0
    [[`3c3b36af0f`](3c3b36af0f)]
    [#12936](#12936).
  * V8 has been updated to 5.8 with forward ABI stability to 6.0
    [[`60d1aac8d2`](60d1aac8d2)]
    [#12784](#12784).

* **Domains**
  * Native `Promise` instances are now `Domain` aware
    [[`84dabe8373`](84dabe8373)]
    [#12489](#12489).

* **Errors**
  * We have started assigning static error codes to errors generated by Node.js.
    This has been done through multiple commits and is still a work in
    progress.

* **File System**
  * The utility class `fs.SyncWriteStream` has been deprecated
    [[`7a55e34ef4`](7a55e34ef4)]
    [#10467](#10467).
  * The deprecated `fs.read()` string interface has been removed
    [[`3c2a9361ff`](3c2a9361ff)]
    [#9683](#9683).

* **HTTP**
  * Improved support for userland implemented Agents
    [[`90403dd1d0`](90403dd1d0)]
    [#11567](#11567).
  * Outgoing Cookie headers are concatenated into a single string
    [[`d3480776c7`](d3480776c7)]
    [#11259](#11259).
  * The `httpResponse.writeHeader()` method has been deprecated
    [[`fb71ba4921`](fb71ba4921)]
    [#11355](#11355).
  * New methods for accessing HTTP headers have been added to `OutgoingMessage`
    [[`3e6f1032a4`](3e6f1032a4)]
    [#10805](#10805).

* **Lib**
  * All deprecation messages have been assigned static identifiers
    [[`5de3cf099c`](5de3cf099c)]
    [#10116](#10116).
  * The legacy `linkedlist` module has been removed
    [[`84a23391f6`](84a23391f6)]
    [#12113](#12113).

* **N-API**
  * Experimental support for the new N-API API has been added
    [[`56e881d0b0`](56e881d0b0)]
    [#11975](#11975).

* **Process**
  * Process warning output can be redirected to a file using the
    `--redirect-warnings` command-line argument
    [[`03e89b3ff2`](03e89b3ff2)]
    [#10116](#10116).
  * Process warnings may now include additional detail
    [[`dd20e68b0f`](dd20e68b0f)]
    [#12725](#12725).

* **REPL**
  * REPL magic mode has been deprecated
    [[`3f27f02da0`](3f27f02da0)]
    [#11599](#11599).

* **Src**
  * `NODE_MODULE_VERSION` has been updated to 57
    (ec7cbaf266)]
    [#12995](#12995).
  * Add `--pending-deprecation` command-line argument and
    `NODE_PENDING_DEPRECATION` environment variable
    [[`a16b570f8c`](a16b570f8c)]
    [#11968](#11968).
  * The `--debug` command-line argument has been deprecated. Note that
    using `--debug` will enable the *new* Inspector-based debug protocol
    as the legacy Debugger protocol previously used by Node.js has been
    removed. [[`010f864426`](010f864426)]
    [#12949](#12949).
  * Throw when the `-c` and `-e` command-line arguments are used at the same
    time [[`a5f91ab230`](a5f91ab230)]
    [#11689](#11689).
  * Throw when the `--use-bundled-ca` and `--use-openssl-ca` command-line
    arguments are used at the same time.
    [[`8a7db9d4b5`](8a7db9d4b5)]
    [#12087](#12087).

* **Stream**
  * `Stream` now supports `destroy()` and `_destroy()` APIs
    [[`b6e1d22fa6`](b6e1d22fa6)]
    [#12925](#12925).
  * `Stream` now supports the `_final()` API
    [[`07c7f198db`](07c7f198db)]
    [#12828](#12828).

* **TLS**
  * The `rejectUnauthorized` option now defaults to `true`
    [[`348cc80a3c`](348cc80a3c)]
    [#5923](#5923).
  * The `tls.createSecurePair()` API now emits a runtime deprecation
    [[`a2ae08999b`](a2ae08999b)]
    [#11349](#11349).
  * A runtime deprecation will now be emitted when `dhparam` is less than
    2048 bits [[`d523eb9c40`](d523eb9c40)]
    [#11447](#11447).

* **URL**
  * The WHATWG URL implementation is now a fully-supported Node.js API
    [[`d080ead0f9`](d080ead0f9)]
    [#12710](#12710).

* **Util**
  * `Symbol` keys are now displayed by default when using `util.inspect()`
    [[`5bfd13b81e`](5bfd13b81e)]
    [#9726](#9726).
  * `toJSON` errors will be thrown when formatting `%j`
    [[`455e6f1dd8`](455e6f1dd8)]
    [#11708](#11708).
  * Convert `inspect.styles` and `inspect.colors` to prototype-less objects
    [[`aab0d202f8`](aab0d202f8)]
    [#11624](#11624).
  * The new `util.promisify()` API has been added
    [[`99da8e8e02`](99da8e8e02)]
    [#12442](#12442).

* **Zlib**
  * Support `Uint8Array` in Zlib convenience methods
    [[`91383e47fd`](91383e47fd)]
    [#12001](#12001).
  * Zlib errors now use `RangeError` and `TypeError` consistently
    [[`b514bd231e`](b514bd231e)]
    [#11391](#11391).