What the Finder sidebar is, and what it is not

The strip down the left of every Finder window is the sidebar, and it is easy to use for years without knowing what it is made of. That matters more than it sounds, because the answer explains several behaviours that otherwise look like bugs: why dragging something out of it does not delete anything, why the same list turns up in Save dialogs, why one Mac shows a folder there and another does not, and why the menu item to bring it back is sometimes greyed out. The sidebar is a list of pointers, shared by the whole system, and everything it can and cannot do follows from that one fact.

A list of aliases, in four sections

Every row in the sidebar is an alias. Apple states the consequence directly:

Sidebar items are aliases to a folder, disk, or file. If you add or remove a sidebar item, the original folder, disk, or file isn't moved from its original location. Source: support.apple.com

Removing a row therefore deletes nothing. The contextual menu on a sidebar row says Remove from Sidebar rather than Move to Trash, which is the interface being honest about what is happening.

The rows are grouped into named sections. Favorites holds the folders and files put there deliberately. iCloud holds iCloud Drive and, where enabled, the Desktop and Documents folders synced through it. Locations holds disks, connected devices, network volumes, and the machine itself. Tags holds the coloured tags selected for display. A Shared section appears when there is something to put in it.

Each section collapses. Hovering the pointer over a section heading reveals a control at the right end that hides or shows everything under it. This is the fastest way to deal with a sidebar that has grown too long to scan, and it is entirely reversible, unlike removing rows.

The distinction between sections is not decorative. Favorites is the only section that accepts arbitrary items by dragging. The others are populated by the system according to what is connected, what is signed in, and which checkboxes are set.

Turning it on, and the dimmed menu item

Option-Command-S hides and shows the sidebar, and the same command sits in the View menu as Show Sidebar or Hide Sidebar. The setting applies to Finder as a whole rather than to the window in front, so switching it on once affects every window, including new ones and windows restored after a restart.

There is one situation that reliably confuses people. When Show Sidebar appears greyed out and cannot be clicked, the cause is that the toolbar is hidden. Apple's own instructions include the fix in parentheses: if Show Sidebar is dimmed, choose View, then Show Toolbar. Option-Command-T toggles the toolbar when a single tab is open. A Finder window with no toolbar is a deliberately stripped down mode, and the sidebar is part of what it strips.

Resizing works by dragging the divider between the sidebar and the file listing. There is no numeric setting for the width and no way to give different windows different widths, which is a recurring source of disappointment for anyone running one narrow window and one wide one.

Width is worth one more note. The sidebar has a minimum width below which it snaps closed entirely, which is why a slightly overenthusiastic drag makes it disappear and look like a bug. Dragging the divider back out brings it straight back with its contents intact. Nothing was reset, and the rows were never touched. The same snap applies in Open and Save dialogs, where the sidebar starts narrower than it does in a Finder window and reaches that threshold sooner.

Two different routes in, and they behave differently

Items reach the sidebar in two ways, and confusing them accounts for most of the questions about it.

The first is the checkbox list. Finder, then Settings, then Sidebar shows every system provided location with a checkbox: the home folder, Applications, Documents, Downloads, Movies, Music, Pictures, the hard disks, external disks, and so on. These are on or off, and nothing else. A location that will not stay in the sidebar is usually one that was never checked here.

The second is dragging. Any folder or disk dragged into the Favorites section stays there. Files and applications need the Command key held down while dragging, which is the detail most people never discover. Control-Command-T adds whatever is currently selected, which is faster than dragging and works from the keyboard.

Order is manual. Rows drag up and down within their section and stay where they are put. There is no alphabetical sort and no automatic ordering by frequency, so a sidebar that has become a mess stays a mess until someone rearranges it.

One consequence of Favorites being drag driven is that it does not survive a migration cleanly. Moving to a new Mac usually brings the checkbox settings across and leaves the dragged in folders looking correct while pointing at paths that may no longer exist in the same form.

One list, shared by every window and every dialog

The sidebar is not a per window feature. There is exactly one list, and it appears in every Finder window at once. It also appears somewhere less obvious:

These items also appear in Open and Save dialogs. Source: support.apple.com

This is the sidebar's strongest feature and its hardest limit at the same time. The strength is that a folder added once is then one click away in every application's save dialog, which is a real saving for a destination used many times a day. The limit is that the list is global. There is no way to have one set of Favorites while working on one project and a different set while working on another. Everything anyone might ever need has to coexist in a single column, and that column is exactly as long as the screen is tall.

The practical response is to treat Favorites as a small number of long lived destinations rather than a project list. Five to ten rows that stay useful for years is a sidebar that works. Thirty rows that turn over every month is a sidebar that has to be scanned like a search result, which defeats the purpose.

Tags and saved searches are also rows

Two kinds of row are not folders at all. Tags appear in their own section, controlled from Finder, then Settings, then Tags, where colours can be renamed and up to seven tags placed in the Control-click shortcut menu. Clicking a tag row shows every file carrying it, from anywhere on the Mac.

Saved searches sit in Favorites and behave the same way. Building a search with criteria rows and clicking Save creates a Smart Folder, and leaving Add To Sidebar selected puts it in the list. Clicking it re-runs the search. A row reading Recent Invoices can therefore be a live query rather than a folder, and nothing in the appearance of the row says which it is.

This is where the sidebar earns its place for people whose files are not organised by folder. A tag row and a smart folder row both answer questions that a folder hierarchy cannot, and both are one click from every save dialog.

Route	How it is created	In Open and Save dialogs	Holds a place or a question
Sidebar favorite	Drag, or Control-Command-T	Yes	A place
Sidebar tag row	Finder Settings, Tags	Yes	A question
Smart Folder in sidebar	Save a search, keep Add To Sidebar	Yes	A question
Finder tab	Command-T in a window	No	A place, until the window closes
Go to Folder	Shift-Command-G, type the path	Yes	A place, typed each time
Recents	Built in, always present	Yes	A question, defined by the system

When rows go missing or stop working

Several failure modes look alike from the outside and have different causes.

A row that has vanished is usually a checkbox that was never set. External disks, connected servers, and the hard disks themselves each have their own entry under Finder settings, Sidebar, and an unchecked box means the item simply never appears no matter what is plugged in. This is the first thing to check when a newly connected drive shows on the desktop but not in the sidebar, because the desktop and the sidebar are governed by two separate lists of checkboxes in two separate panes.

A row that is present but greyed out is normally a network volume that is not currently mounted. Clicking it attempts to reconnect rather than failing, which is the intended behaviour and the reason those rows are left in place rather than removed.

A row that produces an error when clicked is pointing at something that is no longer there. Removing it and dragging the folder back in is the whole repair. There is no repair tool and no need for one.

A sidebar that looks wrong on a second Mac is behaving correctly. The list belongs to the user account, not to the machine, so a new account or a new computer starts from the default set. What comes across during a migration is inconsistent enough that treating the sidebar as something to rebuild deliberately after a move, rather than something that should have survived, saves a certain amount of irritation.

Finally, a sidebar that appears to have reordered itself has usually been dragged by accident. Rows move on a short drag, there is no confirmation, and there is no undo for the reordering specifically. Putting the two or three most used rows at the very top of Favorites reduces the damage, because those are the ones muscle memory reaches for without looking.

What the sidebar cannot do

Three limits are worth naming, because each one sends people looking for a setting that does not exist.

It holds locations, not selections. A row points at a folder. It cannot hold the four files being worked on this week unless each is added individually as a file favorite, and even then the row opens the file rather than revealing it in context.

It has no text. Clicking a sidebar row navigates. It does not produce a path that can be pasted into a terminal, a chat message, or a script. Getting that requires selecting the folder and pressing Option-Command-C, which copies it as a pathname, and that is a different operation in a different place.

It has no state beyond order. A row cannot remember a view mode, a sort order, a scroll position, or an open shell. Everything about the working context has to be rebuilt on arrival. For someone who moves between the same three or four contexts all day, that reconstruction is the actual cost, and no amount of sidebar tidying reduces it.

What to change first

Open Finder settings, go to Sidebar, and turn off every checkbox for a location not opened in the last month, then drag in the two or three folders actually being used and put them at the top. A short sidebar is faster than a complete one. If the part that keeps costing time is rebuilding the working context after arriving somewhere rather than getting there, that is a different problem, and Atriens is built around it. The comparison against the other options is set out in Compared with other file managers.