Finding your way around the vast amount of information sources can be time consuming. The below list of documents is what I would call the essential documents if you want to start your Office 365 journey.

  • Service Descriptions
    A complete description of each service, whats in and whats not. In these documents you’ll will find the answers to most of your questions. It is of particular importance to familiarize yourself with the comparison tables at the end of the documents in order to decide whether to go for a pure cloud or a hybrid solution.
    • E plan - link
    • P plan - link
    • See also the Office 365 Service Updates wiki page - new wiki with a consolidated list of all the updates to the services  -  link
  • Deployment Guidelink.
    How to plan for and execute deployment and migration
  • Developer Guides
    • Exchange Onlinelink
      This document shows how to use exchange web services to programmatically communicate with exchange online. Some key scenarios such as integration with Azure are also documented (see also: Exchange Online for Developers - link)
    • SharePoint Onlinelink
      This guide walks you through some of the rich features that are available to developers and designers in SharePoint Online in Office 365 (see also SharePoint Online: An Overview for Developers - link)
  • Hybrid Environments.
    These documents helps you understand the options for hybrid environments.
    • Designing Hybrid SharePoint Environments with Office 365link
      Hybrid SharePoint environments combine on-premises Microsoft SharePoint Server 2010 with Office 365 SharePoint Online
    • Exchange Deployment Options Whitepaper - link.
      The purpose of this paper is to help you choose how to deploy Microsoft Exchange: as Exchange Server 2010 on-premises, Exchange Online with Microsoft Office 365 in the cloud, or using both in a temporary or permanent hybrid scenario. See also Calendar Sharing Matrix in hybrid Exchange deployment what Free/Busy viewing and Calendar sharing options are available?- link
    • Exchange Hybrid Deployment and Migration with Office 365 (online article) – link
  • Microsoft Office 365 Purchase and Support Guide + Trial Guide.
    These Guides serves as an introduction to the services, the benefits they provide and how to do a trial.
  • Office 365 Buyers Guide for Enterprise Customers - link
    Buying criteria’s and checklist for the decision to move to the cloud

 

You might also want to visit the below sites frequently:

  • Office 365 Techcenter is the one-stop site that provides information and resources for enterprise IT professionals who want to deploy, integrate, and manage: Office 365 services in the cloud or hybrid environments that include a mix of cloud-based services and on-premises deployments of Microsoft Exchange, Lync, Office, or SharePoint - link
  • Office 365 Community Wikis - link
  • Quick Start Online Services is the place for Microsoft Online Services Partner readiness resources. Use this site to evaluate new partner opportunities, learn program details and gain access to key sales and technical content - link
  • The Office 365 Trust Center - link
  • WhyMicrosoft is where you can see how we compare - link