Here are some key features that make Gmail different from other mail applications like Microsoft Outlook or Lotus Notes.
Email conversations instead of multiple messages
Rather than listing each message reply as a new message in your Inbox, Gmail groups a message and its replies in a conversation, which is listed only once. Opening a conversation shows all its messages in a neat stack, which you can easily collapse or expand. When a new reply arrives, the stack grows and the conversation is marked as unread, indicating there’s something new to look at. Grouping messages this way allows you to quickly retrieve all messages of a thread and reduces inbox clutter.
Here's how conversations appear in your Inbox...
...and here's what an opened conversation looks like:
If conversations aren’t for you, you can turn off the feature in your Gmail settings, on the General tab, under Conversation View. To find settings, click the Gear icon in the upper right of your Gmail page.
Labels and stars instead of folders
Instead of organizing messages in folders, you can organize your Gmail conversations by applying labels. The conversation can remain in your Inbox with the label clearly shown. Here's an example:
As shown in the example, if a conversation applies to more than one topic, you can give it multiple labels.
If you'd like to move a labeled conversation out of your Inbox, just select or open the conversation, then click the Archive icon at the top of your Inbox or conversation.
Whether or not a a labeled conversation is archived, you can list all conversations that have a specific label by clicking the label name in the left pane of your Inbox -- similar to opening a folder of messages:
Unlike with folders, if you've applied more than one label to a message, you can retrieve the message by clicking any of those labels.
The Stars feature provides another way to categorize and access messages. Simply click the star icon to the left of any message to highlight it. Keep clicking the star to choose different colors or shapes.
You can then display all your starred messages (of any color or shape) by clicking the Starred label in the left pane:
To select the shapes and colors available for your stars, click the Gear icon in the upper right of your Gmail window, then click Settings and find the Stars section. Choose your stars, then scroll down and click Save Changes.
Archiving online instead of saving to your desktop
With Gmail, you no longer risk running out of space for storing email. Instead, you get 25 GB of online storage space for just your own email and attachments, all hosted on Google’s secure servers. With that much space, you no longer need to save messages on your desktop in PST files or email archives to free up disk space. You can archive messages online instead. Just check a message to select it and then click the Archive icon. This example shows how to archive the second message:
An archived message is removed from your Inbox but you can still find it later by clicking All Mail in the left pane or using search. Or, add labels or stars to messages before you archive them for even easier retrieval.
You might need to click More in the left pane in order to see your All Mail link:
Then click All Mail
Gmail features the same powerful search technology used on the Web to perform accurate keyword searches of all of your email and attachments. Search by keyword, label, date range, or a host of other options. By archiving messages and using search, you can quickly find any message you've ever sent or received without having to create elaborate folder structures or keep unwanted correspondence in your Inbox.
To find messages, simply type in the search box at the top of your Mail window. Or, for more refined searching, click the arrow to Show search options:
Then fill in the easy-to-use search form to find exactly what you're looking for!