the data you collect.

There are three components to this data model -- users, sessions and interactions.

A user is a visitor to your website or app,

a session is the time they spend there,

and an interaction is what they do while they're there.

You can think of users, sessions and interactions as a hierarchy.

Let's talk through the details of this hierarchy using the analogy of a restaurant.

Restaurants have many customers, some that visit for just one meal, and some that visit

regularly.

During each visit, a person can have one or more interactions with the restaurant staff.

A customer that checks in with the host and leaves right away

because no tables are available has just one interaction during that visit.

In another visit, they may check in, get seated, order dinner, and pay the bill.

This visit has four interactions.

Like a restaurant, your website or mobile app also has visitors, or users.

Some users visit just one time, and some visit multiple times.

In Google Analytics, we refer to each visit as a session.

Later in this course, we'll talk in greater detail about how Google Analytics identifies

the same user across multiple sessions.

But for now, it's important to remember two things:

First, there is a relationship between users and sessions,

like the relationship between restaurant customers and their visits.

Second, Google Analytics can recognize returning users from multiple sessions over time,

just like a restaurant staff recognizes its regular customers.

A visit to a restaurant is made up of interactions,

like ordering a meal and paying the bill.

Similarly, a website or app session is made up of individual interactions.

For example, a user might visit your homepage and then leave right away.

This session would have one interaction -- a page view.

In another session, a user might visit your homepage, watch a video, and make a purchase.

That session includes three interactions.

In Google Analytics, we call each individual interaction within a session a "hit."

There are different types of hits -- for example, pageviews, events and transactions.

Each one is designed to collect a different type of data.

You can now see that each interaction that Google Analytics tracks belongs to a session,

and each session is associated with a user.

We'll revisit the three components of the data model -- users, sessions, and interactions

--

as we discuss the Google Analytics platform throughout this course.