Good stuff to know

Acronym Description
ESN
Electronic serial number
The ESN is a unique number that identifies a BlackBerry Smartphone for Code Division Multiple Access (CDMA) and Mobitex® networks. The ESN is printed on the label on the back of the BlackBerry Smartphone underneath the battery.
The first section of the ESN is the service provider distinction code assigned by the Governing Body for Wireless Communications. The second section of the ESN is the serial number of the BlackBerry Smartphone.
The ESN is comparable to the IMEI, which is used to identify BlackBerry smart phones for other networks.
MEID
Mobile Equipment Identifier
The MEID identifies a BlackBerry Smartphone for CDMA and Mobitex networks. It was created to replace ESNs, which are nearing exhaustion.
ICCID
Integrated Circuit Card Identifier
An ICCID is a unique number assigned to each SIM card. To see the ICCID on the BlackBerry Smartphone, go to Options > SIM Card.
IMEI
International Mobile Equipment Identity
The International Mobile Equipment Identity is a unique number that identifies a particular piece of wireless equipment (for example, a BlackBerry Smartphone).
It is 15 digits long. The IMEI is printed on the label on the back of a BlackBerry Smartphone for Global System for Mobile communications® (GSM®)/General Packet Radio Service (GPRS) networks.
The IMEI is comparable to the ESN, which is used to identify BlackBerry smart phones for CDMA and Mobitex networks.
IMSI
International Mobile Subscriber Identity
An IMSI is a unique number that identifies a SIM card. It is 15 digits long and is made up of a 3-digit country code, a 3-digit service provider code, and a 9-digit unique ID.
PIN
Personal identification number
A PIN is a unique number that identifies a BlackBerry Smartphone. It is printed on the label on the back of the BlackBerry Smartphone underneath the battery.
SIM
Subscriber Identity Module
A SIM card is a smart card that identifies the subscriber, the service provider, and the mobile phone number. It is inserted into the BlackBerry Smartphone.
Not all wireless networks use SIM cards (for example, CDMA does not).

HRT is the Host Routing Tables. It is entries sent from the Carrier.
When you highlight the above entry and hit register now, it registers it with the wireless network. Updates the device details onto the rim relay and sends down carrier specific icons or applicants.

PIM this stands for Personal Information Management. A PIM handles your address book, calendar, tasks, and notes. A BlackBerry has PIM because it has these. Your desktop Microsoft Outlook is a PIM software program. Macintosh users have Entourage, as well as simpler PIM components such as iCal. PIM's are frequently designed to synchronize to each other, such as between a BlackBerry and Microsoft Outlook.
Synchronization; is used to maintain the same version of files on multiple computing devices. For example, calendars and address books
On a Blackberry need to be synchronized with the PIM on a computer.
Short Message Service (SMS) is a communications protocol allowing the interchange of short text messages between mobile telephones. SMS text messaging is the most widely used data application on the planet.

Multimedia Messaging Service, MMS for short, is a cellular protocol standard for sending messages that include multimedia objects (images, audio, video, rich text).

Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmission over short distances from fixed and/or mobile devices, creating wireless personal area networks. (PANs).

Wi-Fi Is the trade name for the popular wireless technology used in home networks, mobile networks, video games and other electronic devices that require some form of wireless networking capability
BIS stands for Blackberry Internet Service. Basically, this is a service from your provider that lets you receive email and access the internet on personal Blackberries
BES: Blackberry Enterprise server. Connects to messaging and collaboration software: Microsoft exchange, Lotus Domino, Novell GroupWise, on enterprise networks to synchronize email and PIM Information between desktop and mobile software. Coincidentally, "bes" also happens to be the Dutch word for "berry"
Also referred to as BES setup i.e.. Are you setup BIS or BES?

WAP: Wireless application protocol: used in network communications in a wireless environment. Its main use is to enable access to the Internet from a mobile phone or PDA.
A WAP browser provides all of the basic services of a computer based web browser but simplified to operate within the restrictions of a mobile phone, such as its smaller view screen. WAP sites are websites written in, or dynamically converted to,WML (Wireless Markup Language) and accessed via the WAP browser. Also known as mobile access websites.