Audacity can record live audio through a microphone or mixer, or digitize  recordings from cassette tapes, records or minidiscs. With some sound cards  Audacity can also capture streaming audio.

• Device Toolbar manages multiple input and output devices.
• Level meters can monitor volume levels before, during and after  recording. Clipping can be displayed in the waveform or in a label  track.
• Record from microphone, line input, USB/Firewire devices and others.
• Record computer playback on Windows Vista and later by choosing  "Windows WASAPI" host in Device Toolbar then a "loopback" input.
• Timer Record and Sound Activated Recording features.
• Dub over existing tracks to create multi-track recordings.
• Record at very low latencies on supported devices on Linux by using  Audacity with JACK.
• Record at sample rates up to 192,000 Hz (subject to appropriate  hardware and host selection). Up to 384,000 Hz is supported for  appropriate high-resolution devices on Mac OS X and Linux.
• Record at 24-bit depth on Windows (using Windows WASAPI host), Mac  OS X or Linux (using ALSA or JACK host).
• Record multiple channels at once (subject to appropriate hardware).   

Import and Export

Import sound files, edit them, and combine them with other files or new  recordings. Export your recordings in many different file formats, including  multiple files at once.

• Import and export WAV, AIFF, AU, FLAC and Ogg Vorbis files.
• Fast "On-Demand" import of WAV or AIFF files (letting you start work  with the files almost immediately) if read directly from source.
• Import and export all formats supported by libsndfile such as GSM  6.10, 32-bit and 64-bit float WAV and U/A-Law.
• Import MPEG audio (including MP2 and MP3 files) using libmad.
• Import raw (headerless) audio files using the "Import Raw" command.
• Create WAV or AIFF files suitable for burning to audio CD.
• Export MP3 files with the optional LAME encoder library.
• Import and export AC3, M4A/M4R (AAC) and WMA with the optional  FFmpeg library (this also supports import of audio from video files).

Sound Quality

• Supports 16-bit, 24-bit and 32-bit (floating point) samples (the  latter preserves samples in excess of full scale).
• Sample rates and formats are converted using high-quality resampling  and dithering.
• Tracks with different sample rates or formats are converted  automatically in real time.

Editing

• Easy editing with Cut, Copy, Paste and Delete.
• Unlimited sequential Undo (and Redo) to go back any number of steps.
• Edit and mix large numbers of tracks.
• Multiple clips are allowed per track.
• Label tracks with selectable Sync-Lock Tracks feature for keeping  tracks and labels synchronized.
• Draw Tool to alter individual sample points.
• Envelope Tool to fade the volume up or down smoothly.
• Automatic Crash Recovery in the event of abnormal program  termination.

Accessibility

• Tracks and selections can be fully manipulated using the keyboard.
• Large range of keyboard shortcuts.
• Excellent support for JAWS, NVDA and other screen readers on  Windows, and for VoiceOver on Mac.

Effects

• Change the pitch without altering the tempo (or vice-versa).
• Remove static, hiss, hum or other constant background noises.
• Alter frequencies with Equalization, Bass and Treble, High/Low Pass  and Notch Filter effects.
• Adjust volume with Compressor, Amplify, Normalize, Fade In/Fade Out  and Adjustable Fade effects.
• Remove Vocals from suitable stereo tracks.
• Create voice-overs for podcasts or DJ sets using Auto Duck effect.
• Other built-in effects include:

Echo
Paulstretch (extreme stretch)
Phaser
Reverb
Reverse
Truncate Silence
Wahwah

•  Run "Chains" of effects on a project or multiple files in  Batch Processing mode.

Plug-ins

• Support for LADSPA, Nyquist, VST and Audio Unit effect plug-ins.
• Effects written in the Nyquist programming language can be easily  modified in a text editor - or you can even write your own plug-in.

Analysis

• Spectrogram view modes for visualizing frequencies.
• "Plot Spectrum" command for detailed frequency analysis.
• "Sample Data Export" for exporting a file containing amplitude  values for each sample in the selection.
• Contrast Analysis for analyzing average rms volume differences  between foreground speech and background music.
• Support for adding VAMP analysis plug-ins.