Managed metadata with term store management is an improvement of taxonomy management in Sharepoint 2010. This is a hierarchical collection of centrally managed terms that you can define, and then use as attributes for items in.
.A term set is a collection of related terms
Management of taxonomy takes place within the Term Store Management Tool, which is accessible through either Central Administration or Site Administration.

At top we have the term store, which can contain several term groups. A  term group defines a security boundary, and sets permissions for administration of terms. A group can contain several term sets (up to 1,000). A term set can contain terms (up to 30,000).  Managed metadata terms can be dfined in multiple languages. This is done by distinguishing the term itself from the words that represent the term. A label is a word or a phrase that represents a term. A term can have multiple labels

The management of the taxonomy service takes place in a Term Store management tool, available trough Central administration or site administration. First you need to create a managed metadata service, which sets up a database to be used as the term store, and a connection that  provides access to the service.

Go to central administration and manage service applications. Create a new managed service.

When the service is created select in the list and select the properties option from the ribbon bar.

In the properties edit window set the content hub by entering the url of the sitecollection you want to be the main term store service for yout site collections. Other site collections can subscribe to the content types and use the term store published from the hub site collection. It means you can share content types and terms across site collections. But first the content hub has to be published. Select the manage metadata service connection from the service list and then select properties from the ribbonbar. Check the publish settings below. Then publish the selected  service connection by publish from the ribbonbar.

The hub synchronization runs as a timer job every 15 minutes. If you want to speed up the publishing, you can run the Content Type Hub and Content Type Subscriber jobs manually from the Monitoring page of Central Administration.

To check which service a site collection is subscribing to, go to Site Collection Administration >Content Type Publishing.