The Project window shows all the files related to your project and is your primary way to find application resources and other project files. This window is opened by default when you start a new project. If you can't find it, or it is closed, you can open it via Window > General > Project or use the shortcut key Ctrl + 5 (macOS: Cmd + 5)
You can move windows by clicking on the top of the window. You can dock the window in the Editor, or drag it out of the Editor window to become a floating window.
By clicking 
the button on the upper right, you can choose One ColumnLayout or Two Column Layout.
One ColumnLayout is as follows:
The Tow Column Layout is as follows: The Two Column Layout has an additional panel that shows a visual preview of each file
The left panel of the Project window shows the project's folder hierarchy. When selecting a folder from the list, Unity will display the details in the right panel. Click 
(small triangle) to expand or collapse folders. Hold down the Alt key + click the small triangle arrow to recursively expand or collapse all nested folders.
Assets are displayed as icons in the right panel, and these icons indicate the type of asset (such as scripts, materials, subfolders, etc.). The icons can be resized using the slider at the bottom of the panel, and if the slider is moved to the far left, the icons will be replaced with a hierarchical list view. The blank space to the left of the slider shows the currently selected item, including the item's full path.
Project window toolbar
Create menu : displays a list of resources or other subfolders that can be added to the currently selected folder
Search bar : Use the search bar to search for files in the project. You can choose to search in the entire project (All), the currently selected folder or AssetStore
Search by Type : Select this property to perform a specific search based on type, such as Mesh, Prefab, Scene
Search by Label : Search in the selected label
Hidden package count: This property can switch the visibility of Packages in the Project window
Search filter criteria:
Search filters work by adding additional search terms to the search text. Search terms starting with "t:" filter by the specified resource type, while "I:" filters by tags. If you know exactly what you're looking for, you can enter those search terms directly into the search box without using the menus. Multiple genres or tags can be searched at once. Adding several types will expand the search to include all specified types (i.e. multiple types can be combined by OR logic). Adding multiple tags will narrow the search to items with any of the specified tags
Search Asset Store
The Project Browser 's search can also be applied to assets available in the Unity Asset Store . If you select __Asset Store__ from the menu in the tracer navigation bar , all free and paid assets in the Asset Store that match the query are displayed . Search by type and tag works the same way as Unity projects. The search query term is first checked against the resource name, followed by the resource bundle name, resource bundle label, and resource bundle description in that order (so items with the search term in the name will be ranked higher than items with the search term in the resource bundle description) .
If an item is selected from the list, the item's details will be displayed in the Inspector , along with options to purchase and / or download. Some resource types provide a preview in this section, so you can rotate the 3D model before purchasing. The Inspector also provides an option to view assets in the regular Asset Store window for more details.
