This Developer console is accessed by clicking on the setup (Gear Icon).
Once you click on Developer Console, then you can find a similar page as below:
This page use for the purpose as mentioned below:
- Create Apex Class
- Create Visualforce Page.
- Create Lightning app
- Create Lightning component
- Create Lightning event & token and Interface
- Open execute anonymous window
- To see logs
- To see code coverage
- Query edition to run SOSL & SOQL