Person: Looker provides an integrated development environment, IDE, that developers can use to modify existing and to model new dimensions, measures and Explores for business users to employ in their data analysis approaches. In this section, we'll explore the overall Looker development environment and review the key components for your workflow as a LookML developer. In Looker, business users interact with and experience the Looker instance in production mode while developers make changes and test new features through development mode. Production mode uses the latest production version of Looker. Everyone using a Looker instance in production mode accesses its projects, Explores and content in the same state. LookML project files are read-only in this mode. As a LookML developer, you can use development mode to make changes to projects without affecting anyone else. Development mode accesses a completely separate version of your project files that only you can see and edit. If you're familiar with Git, production mode uses the main branch of a Git repository of the LookML project while development mode uses a separate branch created from the main branch. After testing, changes made by LookML developers in the separate branch can be merged into production so that all users of the Looker instance can access those updates. By default, LookML projects open in production mode. This means that they show the latest version of the project that has been merged into production. To make changes in your LookML projects, you need to enable development mode which is frequently referred to as dev mode. When you're working in development mode, Looker will display a blue banner at the top of the Looker user interface or UI with a message that you're in development mode. As a LookML developer, you have several options to enter development mode. One option is to use the toggle at the bottom-left side of the Looker UI to enter development mode. You can also use the same toggle button to exit development mode and return to production mode. There is also a keyboard shortcut, control plus shift plus D. Alternatively, at the top-left side of the Looker user interface, you can click on develop menu to see the options and then select projects. Then once you are on the projects page, you can turn on development mode by clicking on the develop option from the top menu bar and using the toggle button for development mode. From the projects page, you can also click on a specific project name such as training_ecommerce to open it within the Looker integrated development environment, IDE. An IDE is an industry term for an application in which software engineers or developers can write and test their code. Looker has its own built-in IDE in which developers can write LookML. The Looker IDE displays six navigation options on the left-side panel. We'll walk through each option to understand the functionality that it provides for LookML developers. The first option, represented by the folder icon, is the file browser. This displays all the LookML project files in the folder hierarchy. Depending on the complexity of the project, you could see dozens or even hundreds of files within many folders and levels of subfolders. At your company with your own development team, you can decide on any kind of folder structure that would be most intuitive for your workflows. The second option, represented by the compass icon, is the object browser. The object browser organizes project files by LookML project type in the project. Each model can be expanded to show the Explores within. Furthermore, each Explore can be expanded to reveal the views that are joined together, and each view can be expanded to display the dimensions and measures. This is really useful when you need to find a specific field or view being used within an Explore especially if you have many similarly named objects in the model. You may also need to visualize in a sense in how many Explores the same view is being used or which models have the same or similar Explores. Next is the find and replace option. You can search for a specific word, like count, and see where and how many times this appears throughout all the files in your entire project. You can also batch-replace all instances of a text string with something else. The fourth option in the IDE shows the available Git actions. These options allow you to switch between Git branches, view past commits by yourself and fellow developers, view the project on GitHub or whichever Git provider you use at your company, and more. The next option displays the project settings. As a LookML developer, you can see the configurations, but only a Looker admin can change them. For example, admins can specify what is or isn't required to commit code, enable pull requests if your team prefers to do code reviews before deploying to production, change the Git connection and more. The last option is the deployment manager. This page lets you see the recent changes that have been deployed to the production environment. Additional details about the changes such as the user and date associated with the change are also available on the this page. In summary, as a LookML developer, you can make and test changes in your organization's Looker instance in development mode without impacting the production environment. When working in your organization's Looker instance, be mindful of whether you're currently in production mode or development mode. The Looker IDE and Explore menus will offer different features and options in production versus development mode. Depending on your permissions and local code differences, you may even see different lists of projects, project files and Explores. With this understanding of the differences between production and development mode, we hope that you have fun exploring the LookML projects in your organization's Looker instance.