What is the use of sessions in google analytics?

A session is defined as a group of interactions one user takes within a given time frame on your website. Google Analytics defaults that time frame to 30 minutes. Meaning whatever a user does on your website before they leave equals one session.

A session is a group of user interactions with your website that take place within a given time frame. For example a single session can contain multiple page views, events, social interactions, and ecommerce transactions.

You can think of a session as the container for the actions a user takes on your site.

Many interactions can happen within one visit.
A single user can open multiple sessions. Those sessions can occur on the same day, or over several days, weeks, or months. As soon as one session ends, there is then an opportunity to start a new session. There are two methods by which a session ends:

Time-based expiration:
After 30 minutes of inactivity
At midnight
Campaign change:
If a user arrives via one campaign, leaves, and then comes back via a different campaign.

A session is defined as a group of interactions one user takes within a given time frame on your website. Google Analytics defaults that time frame to 30 minutes. Meaning whatever a user does on your website (e.g. browses pages, downloads resources, purchases products) before they leave equals one session.

Session is nothing but how much time user withstand in our particular website is know as sessions its play an major role in google analytics