A Zap is the link between your apps on Zapier. A Zap is a noun, not a verb. For example, New Salesforce Contacts to Add MailChimp Subscriber would be an example of a Zap. If you wanted to move those same Salesforce contacts to an additional MailChimp account or an additional MailChimp list, that would be a second Zap. You can see all your Zaps from your Dashboard. A Zap can only have one Trigger, but multiple Actions.
An Account allows Zapier to access your data inside another app. You can have multiple Accounts for the same app. Each Account can have a label which helps you distinguish them inside Zapier.
A task is a single action performed by Zapier. A single Zap can perform many tasks. If your Zap's action is to create new Google Contacts, then you'll use one task for every contact that is created.
A Trigger is the event that starts a Zap. For example, if you want to automate sending a text message each time you receive an email, the "new email in inbox" is the Trigger.
An Action is an event a Zap performs. For example, if you want to send an SMS each time you receive an email, "send text message" is the Action.
A Filter is an optional feature you apply to a Zap to only make it fire when a certain condition is met. For example, if you're sending a text message when you receive a new email, you could use a Filter that only sends a text message when the email received is from a certain address.
The Zap Editor allows you to create a Zap from scratch, giving you the ability to choose the Trigger App, Trigger, Action App, Action and, optionally, apply any Filters.
An App is a web service or application, such as Google Docs, Evernote or Salesforce. Zapier offers integrations for over 750 apps, letting you move data between them or automate repetitive tasks.
A single step Zap has one Trigger and one Action. If the Zap has more than one Action or includes Filters or Searches it is considered a Multi-Step Zap and is not available on the Zapier Free plan.