HHexadecimal (sometimes as lowercase h)
H&KHug and Kiss
HAHorn Alert
HABUHave A Better 'Un
HACKHacking And Computer Krashing
HAGNHave A Good Night
HAGSHerbally Aroused Gynecological Squad
HAGUHave A Good 'Un
HAIHardware Accelerator Interface
HAKhugs and kisses
HALHardware Abstraction Layer
HALEHacker's Against Law Enforcement
HAMHome Amature Mechanic / Hybrid Access Method
HANHome Area Network
HANDHave A Nice Day
HASCSHarvard Arts and Sciences Computer Services
HASPHouston Automatic Spooling Priority
HATEHighly Artistically Talented Enterprises
HBAHost Bus Adapter
HBFGHost Behavior Functional Group (ATM Forum)
HBOHome Box Office
HCDSHigh Capacity Digital Service
HCFHalt and Catch Fire
HCIGHealth Care Industry Group
HCLHardware Compatability List / Hop Count Limit
HCLRGHEFC's Colleges Learning Resources Group
HCOHigh Capacity Output
HCSHard Clad Silica / Header Check Sequence
HCSDSHigh Capacity Satellite Digital Service
HCSSHigh Capacity Storage System
HCTDSHigh Capacity Terrestrial Digital Service
HDHard Disk (drive) / Hard Drive / High Density
HDAHead Disk Assembly
HDB3High Density Bipolar - Three (zeros)
HDDHigh Double Density / Hard Disk Drive
HDKHippy Dippy Klub
HDLHardware Description Language
HDLCHigh-level Data Link Control
HDMHardware Device Module
HDMLHandheld Device Markup Language
HDRHost Data Replicator
HDSCHigh Density Signal Carrier
HDSLHigh-bit-rate Digital Subscriber Line / High-data-rate Digital Subscriber Line
HDTHost Digital Terminal
HDTPHandheld Device Transport Protocol
HDTVHigh Definition TeleVision
HDXHalf Duplex
HEAPHome Energy Assistance Program
HECHeader Error Check / Header Error Control
HEFCEHigher Education Funding Council for England
HEFCWHigher Education Funding Council for Wales
HEHOHigh End Hop Off
HELHardware Emulation Layer / Header Extension Length
HEMPHigh - altitude ElectroMagnetic Pulse
HEMSHigh - Level Entity Management System / High - Level Entity Monitoring Sys
HENCEHeterogeneous Network Computing Environment (usually as HeNCE)
HENSAHigher Education National Software Archive
HEPHub Expansion Port
HEPNETHigh Energy Physics NETwork
HEQCHigher Education Quality Council
HESAHigher Education Statistics Agency
HETLAHighly Extended Three Letter Acronym
HEUHacking at the End of the Universe (convention)
HFHands Free / High Frequency
HFCHybrid Fiber-Coaxial / Hierarchical File System
HGAHercules Graphics Adapter
HGCHercules Graphics Card
HHISHanging Head in Shame
HHO1/2KHa Ha Only Half Kidding
HHOJHa Ha Only Joking
HHOKHa Ha Only Kidding
HHOSHa Ha Only Serious
HIBCCHealth Industry Business Communications Council
HICHeadend Interface Converter / Hybrid Integrated Circuit
HICOMHigh technology Communication
HID/LODHigh-Density / Low-Density (tariff)
HILIHigher - Level Interface
HIPOHierarchy plus Input - Process - Output (charts)
HIPPIHIgh Performance Parallel Interface
HITHackers In Touch
HIWTHHate it when that happens
HIYAhello [in most any language]
HL7ECFHealth Level Seven Enterprise Communications Framework
HLFHigh Level Format(ting)
HLIHigh-speed LAN Interconnect
HLLHigh Level Language (API)
HLLAPIHigh Level Language Application Program(ing) Interface
HLOLARAWCHAWMPHysterically Laughing Out Loud And Rolling Around While Clapping Hands And Wetting My Pants (courtesy ecco in action)
HLPIHigher Layer Protocol Identifier
HMAHigh Memory Area
HMDHead Mounted Display
HMIHorizontal Motion Index / Hub Management Interface / Human - Machine Interface
HMLHuman - Machine Language
HMMPHyperMedia Management Protocol
HMMSHyperMedia Management Schema
HMOFGor HMFG Holy Mother Of Fucking God.
HMOSHigh density Metal Oxide Semiconductor
HMPHost Monitoring Protocol
HMUXHybrid Multiplexer
HNHost to Network
HNDSHybrid Network Design System
HNPAHome Numbering Plan Area
HNSHospitality Network Service
HOBHierarchical Operational Binding
HOBICHotel Billing Information Center
HOBISHotel Billing Information System
HOHHash Of Hashes
HOLHead Of Line
HPHewlett Packard / Home Page ( on the WWW ) / Hit Points (Common MUD term)
HPAHacker/Phreakers Association
HPADHost Packet Assembler / Disassembler
HPCHandheld Personal Computer
HPCAHigh Performance Computing Act
HPCCHigh Performance Computing and Communications program
HPCCITHigh Performance Computing
HPCGHigh Performance Computing Group
HPFCHigh Performance Functional Computing
HPFSHigh Performance File System
HPGLHewlett Packard Graphics Language
HP-GLHewlett Packard Graphics Language
HPIBHewlett Packard Interface Bus
HPIUGAHewlett Packard International Users Group Association
HPMHigh Power Microwave
HPOHigh Performance Option
HPOFSHigh Performance Optical File System
HPPPNHewlett Packard Private Packet Network
HPRHigh Performance Routing
HPSHardware Product Services / High Performance Systems
HPSSHigh Performance Switching System
HPTHigh-Pressure Tin
HRHorizontal Rule / Human Resources
HRCHybrid Ring Control
HRDHigh Resolution Diagnostic Diskette / Human Resources Development
HRPFHexadecimal Reference Publication Format
HRSCHigh Resolution Stereo Camera
HRUHackers 'R' Us
HSCHierarchical Storage Controller
HSDCHigh - Speed Data Card
HSFHigh Sierra Format
HSIKHow Should I Know
HSIMHigh Speed Interface Module (W6)
HSLANHigh - Speed Local Area Network
HSMHierarchical Storage Management
HSSDSHigh-Speed Switched Digital Service
HSSIHigh Speed Serial Interface
HSSPHigh Speed Switched Port
HSTHigh Speed Technology
HTHorizontal Tabulation (ASCII)
HTCIAHigh Tech Computer Investigators Association
HTHHappy To Help / Hope This Helps
HTMHTML Extention
HTMLHyperText Mark-up Language
HTTPHyperText Transfer Protocol
HTTPDHyperText Transfer Protocol Daemon
HTXHTML Extention
HUHigh Usage
HUBHead Up Butt
HUTGHigh Usage Trunk Group
HVACHeating Ventilation and Air Conditioning
HVMHigh Volume Manufacturing
HWGHTML Writers Guild
HWS(PEST)Husband Wants Sex (Please Excuse Slow Typing)
HWSPESTHusband Wants Sex (Please Excuse Slow Typing)
HYCFAPMSFTJHonestly you couldn't find a person more suited for the job.
HZHertz (usually as Hz)


HAC                :- Hindustan Aluminium Corporation

HADP             :- Hill Area Development Programme

HAL                :- Hindustan Aeronautics Limited

HARK            :- Handy Audio Reach Kit System

HARTRDN    :- Haryana State Electricity Development Corporation Limited

HCF                :- Highest Common Factor

HDFC             :- Housing Development Finance Corporation

HDPE             :- High Density Poly Ethylene

HDTV             :- High Definition Television

HEC                :- Heavy Engineering Corporation

HEL                :- Heavy Electricals Limited

HESH             :- High Explosive Squash Head

HISA              :- Hero Indian Sports Academy

HIV                :- Human Immuno-deficiency Virus

HMI               :- Himalayan Mountaineering Institute

HMT              :- Hindustan Machine Tools

HPTS             :- High Power Television Transmitter System

HTR              :- High Temperature Reactor

HUDCO         :- Housing and Urban Development Corporation

HYVS             :- High Yield Variety Seeds