Below are list of Salesforce permissions with short description of what each allows a user to do.
Links are provided for more in depth description for each permission.

• Access to Chatter For Sharepoint -Allow users to access Chatter for SharePoint
• Activate Contracts – Change a contract status to Activated
• Activate Orders – Change order status to Activated
• Allow View Knowledge – Allow user to view knowledge articles
• API Only Users – Access Salesforce.com only through a Salesforce.com API
• Approve Contracts – Approve or rejects a contract from a related list
• Assign Permission Sets  – Assign permission sets to users
• Bulk API Hard Delete – Delete records in the Bulk API without storing them in the Recycle Bin
• Chatter Internal User –
• Configure Custom Recommendations – Add custom recommendations in the feed, motivating users to get engaged and take action
• Connect Organization to Environment Hub – Allows a user to connect this organization to an Environment Hub
• Create and Customize List Views – Create list views; modify and delete own list views
• Create and Customize Reports – Create, edit and delete reports
• Create and Own New Chatter Groups – Create and own new chatter groups
• Create and Set Up Communities – Create communities, manage community-wide settings, membership, login and registration, branding, and associated Site.com site
• Create and Share Content Deliveries for Chatter File – Share a Chatter file with anyone by creating a file link and sending it via email or IM
• Create and Upload Change Sets – Create, edit and upload outbound change sets
• Create AppExchange Packages – Create packages that can be distributed through AppExchange
• Create Dashboard Folders – Create dashboard folders and manage these folders if sharing rights allow
• Create Libraries – Create Salesforce CRM Content libraries
• Create Report Folders – Create report folders and manage these folders if sharing rights allow
• Delete Activated Contracts – Delete contracts, regardless of their status
• Deliver Uploaded Files and Personal Content – Enables non-Content users to create content deliveries and enables Salesforce CRM Content users to create content deliveries using documents in their private library
• Deploy Change Sets – Deploy inbound change sets
• Download AppExchange Packages – Install or uninstall AppExchange packages as system administrators
• Drag-and-Drop Dashboard Builder – Create, edit, and delete dashboards through the drag-and-drop dashboard builder interface
• Edit Case Comments – Edit their own case comments but not other user’s comments
• Edit Events – Create, edit, and delete events
• Edit HTML Templates – Create, edit, and delete HTML email templates
• Edit My Dashboards – Edit, move, save, and delete user’s own dashboards in shared folders
• Edit My Own Posts – Allow users to edit their own feed items
• Edit My Reports – Edit, move, save and delete user’s own reports in shared folders
• Edit Opportunity Product Sales Price – Change the sales price on opportunity line items
• Edit Posts on Records I Own – Allow users to edit feed items they manage
• Edit Read Only Fields – Edit fields that are read only due to page layouts or field-level security
• Edit Self-Service Users – Enable and disable contacts for Self-Service and Customer Portal access
• Edit Tasks – Create, edit and delete tasks
• Email-Based Identity Confirmation Option – Provides an option to use email to confirm identity, even if the user has a verified phone number
• Enable Work.com Calibration – Allow Work.com users to access Work.com Calibration functionality
• Export Reports – Use Export Details and Printable View to export reports
• Import Personal Contacts – Import personal accounts and contacts
• Import Solutions – Import solutions for the organization
• Insert System Field Values for Chatter Feeds – Set the author or creation date for a Chatter post or comment
• Invite Customers To Chatter – invite customers to Chatter
• IP Restrict Requests – Restrict what IP addresses can access the CRM Portal
• Knowledge One – Replaces the Articles tab with the Knowledge tab
• Lightning Experience User – Access the Salesforce Lightning Experience.  Users with this permission can individually enable or disable this user interface.
• Manage Articles – Create, edit, assign, publish, delete and archive Salesforce Knowledge articles.
• Manage Auth. Providers – Create and edit Auth. Providers
• Manage Billing – Purchase additional licenses and features
• Manage Business Hours Holidays – Create, edit, and delete business holidays
• Manage Call Centers – Create, import, edit and delete a call center configuration
• Manage Cases – Administer case settings, including Email-to-Case and mass transfer for cases
• Manage Categories – Define and modify solution categories settings
• Manage Chatter Messages – Access all users’ messages sent in Chatter
• Manage Communities –  Access Community Management to view community dashboards and set up Reputation point system and levels
• Manage Connected Apps – Manage, create, edit and delete connected applications
• Manage Content Permissions – Create, edit and delete library permissions in Salesforce CRM Content
• Manage Content Properties – Create, edit and delete custom fields in Salesforce CRM Content
• Manage Custom Permissions – Create, edit, and delete custom permissions
• Manage Custom Report Types – Create, edit, and delete custom report types
• Manage Dashboards – Create, edit and delete the user’s personal dashboards
• Manage Dashboards in Public Folders – Create, edit, delete dashboards, and manage their sharing in all public folders
• Manage Data Categories – Create, edit, and delete data categories
• Manage Data Integrations – Monitor or abort Bulk API jobs
• Manage Dynamic Dashboards – Create, edit, and delete dynamic dashboards
• Manage Email Client Configurations – Create, edit, and delete Outlook configurations for Salesforce for Outlook
• Manage Encryption Keys – Manage tenant secrets
• Manage Exchange Configurations – Create, edit, and delete Exchange configurations for S2X
• Manage Force.com Flow – Create and edit Force.com Flows
• Manage Internal Users – Create and edit internal users
• Manage IP Addresses – Create, edit, and delete trusted IP ranges
• Manage Knowledge Article Import/Export – Allows user to manage all the Knowledge Article Import/Export
• Manage Leads – Change the status of multiple leads in a list view
• Manage Letterheads – Create, edit, and delete letterheads for HTML emails
• Manage Logging Access Policies – Specify the login access policies that apply to administrators and support organizations
• Manage Macros Users Can’t Undo – Create, update, and run macros that include irreversible instructions
• Manage Mobile Configurations – Access Salesforce Classic features
• Manage Package Licenses – Manage package licenses in subscriber organizations
• Manage Profiles and Permission Sets – Create, edit and delete profiles and permission sets
• Manage Promoted Search Terms – create, edit and delete promoted search terms
• Manage Public Documents – Create, edit, and delete folders for public documents
• Manage Public List Views – Create, edit, and delete public list views.
• Manage Public Reports – Create, edit and delete public reports
• Manage Public Templates – Create, edit, and delete text emails, mail merge templates, and folders for public email templates
• Manage Published Solutions – Create, edit and delete publicly accissible solutions
• Manage record types and layouts for Files – Create, edit and delete content types in Salesforce CRM Content
• Manage Reporting Snapshots – Create, edit, and delete reporting snapshots
• Manage Reports in Public Folders – Create, edit, delete reports and manage their sharing in all public folders
• Manage Roles – Create, edit and delete roles
• Manage Salesforce CRM Content – Create, edit and delete libraries and library memberships
• Manage Salesforce Knowledge – Manage Salesforce Knowledge settings, and create, edit and delete article types
• Manage Self-Service Portal – Manage Self-Service portal settings and reports
• Manage Sharing – Create, edit, and recalculate sharing rules, edit organization-wide defaults, and enable the external sharing model
• Manage Synonyms – Create, edit and delete synonym groups
• Manage Two-Factor Authentication – Manage the time-based token secret for two-factor authentication
• Manage Unlisted Groups – View and moderate unlisted Chatter groups
• Manage Users – Create, edit, and deactivate users, and manage security settings, including profiles
• Mass Edits from Lists – Edit multiple records simultaneously from a list with inline editing
• Mass Email – Send mass emails to contacts and leads
• Merge Topics – Merge one or more topics
• Moderate Chatter – Deactivate Chatter Free users, assign moderator privileges to Chatter Free users, and remove posts
• Modify All Data – Create, edit, and delete all organization data, regardless of sharing settings
• Modify Secure Agents – Allow user to make changes to Secure Agents
• Password Never Expires – Prevent the user’s password from expiring
• Report Builder – Create, edit and delete reports through the drag and drop report builder interface
• Reset User Passwords and Unlock Users – Unlock users whose accounts are locked, and reset user passwords
• Run Flows – run flows
• Run Macros on Multiple Records – run macros on multiple records at the same time
• Run Reports – run reports and dashboards
• Schedule Dashboards – Schedule when dashboards refresh, and send email notifications that include refreshed dashboards in HTML format
• Schedule Reports – Run reports in the background, and export results as a CSV or Excel file on completion
• Select Files from Salesforce – Selecting a Salesforce file is an option when attaching a file
• Send Email – Send email to a singlet contact or lead
• Send Outbound Messages – Send outbound messages to an external Web service API
• Send Stay-in-Touch Requests – Send Stay-in-Touch update emails
• Set Audit Fields upon Record Creation – Set audit fields, such as Created By and Last Modified By, when you create a record (API only)
• Share internal Knowledge Articles externally – Allow user to share internal Knowledge articles externally
• Show Custom Sidebar On All Pages – Display a custom sidebar on all pages in Salesforce.com
• Tag Manager – Manage the configuration of private and public tags
• Transfer Cases – Change a case’s owner
• Transfer Leads – Change a lead’s owner
• Transfer Record – Change the owner of most records
• Two-Factor Authentication for API Logins – Require users to enter a time-based token instead of the emailed security token in the API
• Two-Factor Authentication for User Interface Logins – Require users to enter a time-based token during login
• Update Records with Inactive Owners – Update owner and sharing-based fields on records with inactive owners
• Upload AppExchange Packages – upload packages to AppExchange for distribution
• Use Identity Features – Gives the user access to Identity features such as App Launcher
• User Team Reassignment Wizards – Mass reassign account team and opportunity team members
• Via Data Categories – View the Data Categories page
• View All Data – View all organizational data, regardless of sharing settings
• View All Users – View all users, regardless of sharing settings
• View Dashboards in Public Folders – View and access dashboards in public folders, which does not include others’ personal folders
• View Encrypted Data – View the value of encrypted fields in plain text
• View Event Log Files – Get CSV event log files via the API
• View Help Link – Allow user to view help link
• View My Team’s Dashboards – View dashboards owned by people under them in the role hierarchy
• View Reports in Public Folders – View and access reports in public folders, which does not include others’ personal folders
• View Setup and Configuration – View the App Setup and Administrative Settings pages
• Weekly Data Export – Run the weekly data export service