What is Tracker?
By using Tracker, you no longer have to remember where you've left your files. To locate a file you only need to remember something about it, such as a word in the document or the artist of the song. This is because as well as searching for files in the traditional way, by name and location, Tracker searches files' contents and metadata.
Metadata, or data about data includes attributes specific to each file, such as the artist of a song or the author of a document. Tracker reads this metadata, and places it into an index, which allows searches to be lightning fast. Tracker updates its index automatically, so search results are always accurate up-to-the-moment.
Tracker doesn't stop there -- by allowing you to attach your own metadata to files it frees you from having to keep everything in highly organised folders. You can add one or many 'tags' to files, effectively grouping several files in your filesystem even if they are located in different folders. So, tagging can be much easier and more flexible than fitting your information into preconceived categories or folders.
What are tags?
Tags are one-word labels that you can assign to any file to help you categorize and remember them. Tags are a little bit like the metadata tracker extracts from within the file, but they're chosen by you. You can assign as many tags to a file as you like and rename or delete the tags later.
What does Tracker offer?
- Application-neutral and desktop-neutral tagging. Tagging support 'for free' in any application that uses tracker, such as Nautilus  and file-chooser dialogs.
- A cross-application metadata database. If applications chooses to use Tracker as their metadata database and indexer, they would see signifigant improvements. Users would no longer need to add a MP3 they have downloaded to Rhythmbox, nor a photo they have taken to f-spot, these items would be detected and imported automatically.
- Users may completely move away from a folder-hierarchy based home folder, and instead organise their data into collections using tags. The combination of tagging support in the file-chooser, tagging awareness in Nautilus, or even a tag based filesystem using FUSE could allow radical exploration of new desktop ideas.
- Improved performance. With an always running indexer application start up time could be dramatically reduced in instances where applications scan or parse a number of files on disk. For example alacarte could use tracker as its desktop file parser, or rhythmbox could use tracker as its song index. In addition by using a DBus based API one can take advantage of asynchronous replies for improved GUI responsiveness.
- In future, of if necessary for inclusion, libtracker may be able to be considered part of the platform with appropriate API guarentees. Underneath, the Tracker DBus interface may be more free to change and expand to application developers needs.
- Written in C for maximum efficiency.
- Designed and built to run well on lower-memory systems with typically 128MB or 256MB memory. Typical RAM usage is 4-6 MB.
- Runs at nice+19 so it should have a minimal impact on your system.
- Indexers run in separate processes, so a crash in an indexer will not bring down the daemon.