If you are on a Debian flavor of Linux (Ubuntu, Mint, etc.), you can install CouchDB with:

$ sudo apt-get install couchdb
On a Mac you can do:

$ brew install couchdb
On Windows, you should install from the CouchDB web site.

A CouchDB alternative: PouchDB Server

If you have trouble installing CouchDB, you can also install PouchDB Server, which is a drop-in replacement for CouchDB that uses PouchDB under the hood:

$ npm install -g pouchdb-server
$ pouchdb-server --port 5984
PouchDB Server is currently experimental, and we do not recommend it for production environments.

CORS is a web technology that allows web sites to use resources from another domain. You will want to enable this in your CouchDB before continuing, because otherwise PouchDB will not work unless it's served from exactly the same domain as CouchDB.

Enabling CORS is easy. Just install this handy script:

$ npm install -g add-cors-to-couchdb
And run it:

$ add-cors-to-couchdb
If you installed PouchDB Server, CORS is enabled by default, and this step is not necessary.

<script src="bower_components/pouchdb/dist/pouchdb.min.js"></script>