| CODE | ABBREVIATION |
| H | Hexadecimal (sometimes as lowercase h) |
| H&K | Hug and Kiss |
| H/M | Hotel/Motel |
| HA | Horn Alert |
| HABU | Have A Better 'Un |
| HACK | Hacking And Computer Krashing |
| HAGN | Have A Good Night |
| HAGS | Herbally Aroused Gynecological Squad |
| HAGU | Have A Good 'Un |
| HAI | Hardware Accelerator Interface |
| HAK | hugs and kisses |
| HAL | Hardware Abstraction Layer |
| HALE | Hacker's Against Law Enforcement |
| HAM | Home Amature Mechanic / Hybrid Access Method |
| HAN | Home Area Network |
| HAND | Have A Nice Day |
| HASCS | Harvard Arts and Sciences Computer Services |
| HASP | Houston Automatic Spooling Priority |
| HATE | Highly Artistically Talented Enterprises |
| HBA | Host Bus Adapter |
| HBFG | Host Behavior Functional Group (ATM Forum) |
| HBO | Home Box Office |
| HC | HyperChannel |
| HCDS | High Capacity Digital Service |
| HCF | Halt and Catch Fire |
| HCIG | Health Care Industry Group |
| HCL | Hardware Compatability List / Hop Count Limit |
| HCLRG | HEFC's Colleges Learning Resources Group |
| HCO | High Capacity Output |
| HCS | Hard Clad Silica / Header Check Sequence |
| HCSDS | High Capacity Satellite Digital Service |
| HCSS | High Capacity Storage System |
| HCTDS | High Capacity Terrestrial Digital Service |
| HD | Hard Disk (drive) / Hard Drive / High Density |
| HDA | Head Disk Assembly |
| HDB3 | High Density Bipolar - Three (zeros) |
| HDD | High Double Density / Hard Disk Drive |
| HDK | Hippy Dippy Klub |
| HDL | Hardware Description Language |
| HDLC | High-level Data Link Control |
| HDM | Hardware Device Module |
| HDML | Handheld Device Markup Language |
| HDR | Host Data Replicator |
| HDSC | High Density Signal Carrier |
| HDSL | High-bit-rate Digital Subscriber Line / High-data-rate Digital Subscriber Line |
| HDT | Host Digital Terminal |
| HDTP | Handheld Device Transport Protocol |
| HDTV | High Definition TeleVision |
| HDX | Half Duplex |
| HEAP | Home Energy Assistance Program |
| HEC | Header Error Check / Header Error Control |
| HEFCE | Higher Education Funding Council for England |
| HEFCW | Higher Education Funding Council for Wales |
| HEHO | High End Hop Off |
| HEL | Hardware Emulation Layer / Header Extension Length |
| HEMP | High - altitude ElectroMagnetic Pulse |
| HEMS | High - Level Entity Management System / High - Level Entity Monitoring Sys |
| HENCE | Heterogeneous Network Computing Environment (usually as HeNCE) |
| HENSA | Higher Education National Software Archive |
| HEP | Hub Expansion Port |
| HEPNET | High Energy Physics NETwork |
| HEQC | Higher Education Quality Council |
| HESA | Higher Education Statistics Agency |
| HETLA | Highly Extended Three Letter Acronym |
| HEU | Hacking at the End of the Universe (convention) |
| HF | Hands Free / High Frequency |
| HFC | Hybrid Fiber-Coaxial / Hierarchical File System |
| HGA | Hercules Graphics Adapter |
| HGC | Hercules Graphics Card |
| HHIS | Hanging Head in Shame |
| HHO1/2K | Ha Ha Only Half Kidding |
| HHOJ | Ha Ha Only Joking |
| HHOK | Ha Ha Only Kidding |
| HHOS | Ha Ha Only Serious |
| HIBCC | Health Industry Business Communications Council |
| HIC | Headend Interface Converter / Hybrid Integrated Circuit |
| HICOM | High technology Communication |
| HID/LOD | High-Density / Low-Density (tariff) |
| HILI | Higher - Level Interface |
| HIPO | Hierarchy plus Input - Process - Output (charts) |
| HIPPI | HIgh Performance Parallel Interface |
| HIT | Hackers In Touch |
| HIWTH | Hate it when that happens |
| HIYA | hello [in most any language] |
| HL7ECF | Health Level Seven Enterprise Communications Framework |
| HLF | High Level Format(ting) |
| HLI | High-speed LAN Interconnect |
| HLL | High Level Language (API) |
| HLLAPI | High Level Language Application Program(ing) Interface |
| HLOLARAWCHAWMP | Hysterically Laughing Out Loud And Rolling Around While Clapping Hands And Wetting My Pants (courtesy ecco in action) |
| HLPI | Higher Layer Protocol Identifier |
| HMA | High Memory Area |
| HMD | Head Mounted Display |
| HMI | Horizontal Motion Index / Hub Management Interface / Human - Machine Interface |
| HML | Human - Machine Language |
| HMMP | HyperMedia Management Protocol |
| HMMS | HyperMedia Management Schema |
| HMOFG | or HMFG Holy Mother Of Fucking God. |
| HMOS | High density Metal Oxide Semiconductor |
| HMP | Host Monitoring Protocol |
| HMUX | Hybrid Multiplexer |
| HN | Host to Network |
| HNDS | Hybrid Network Design System |
| HNPA | Home Numbering Plan Area |
| HNS | Hospitality Network Service |
| HOB | Hierarchical Operational Binding |
| HOBIC | Hotel Billing Information Center |
| HOBIS | Hotel Billing Information System |
| HOH | Hash Of Hashes |
| HOL | Head Of Line |
| HOMPR | Hang On |
| HP | Hewlett Packard / Home Page ( on the WWW ) / Hit Points (Common MUD term) |
| HPA | Hacker/Phreakers Association |
| HPAD | Host Packet Assembler / Disassembler |
| HPC | Handheld Personal Computer |
| HPCA | High Performance Computing Act |
| HPCC | High Performance Computing and Communications program |
| HPCCIT | High Performance Computing |
| HPCG | High Performance Computing Group |
| HPFC | High Performance Functional Computing |
| HPFS | High Performance File System |
| HPGL | Hewlett Packard Graphics Language |
| HP-GL | Hewlett Packard Graphics Language |
| HPIB | Hewlett Packard Interface Bus |
| HPIUGA | Hewlett Packard International Users Group Association |
| HPM | High Power Microwave |
| HPO | High Performance Option |
| HPOFS | High Performance Optical File System |
| HPPPN | Hewlett Packard Private Packet Network |
| HPR | High Performance Routing |
| HPS | Hardware Product Services / High Performance Systems |
| HPSS | High Performance Switching System |
| HPT | High-Pressure Tin |
| HQ | Headquarters |
| HR | Horizontal Rule / Human Resources |
| HRC | Hybrid Ring Control |
| HRD | High Resolution Diagnostic Diskette / Human Resources Development |
| HRPF | Hexadecimal Reference Publication Format |
| HRSC | High Resolution Stereo Camera |
| HRU | Hackers 'R' Us |
| HSC | Hierarchical Storage Controller |
| HSDC | High - Speed Data Card |
| HSF | High Sierra Format |
| HSIK | How Should I Know |
| HSIM | High Speed Interface Module (W6) |
| HSLAN | High - Speed Local Area Network |
| HSM | Hierarchical Storage Management |
| HSSDS | High-Speed Switched Digital Service |
| HSSI | High Speed Serial Interface |
| HSSP | High Speed Switched Port |
| HST | High Speed Technology |
| HT | Horizontal Tabulation (ASCII) |
| HTCIA | High Tech Computer Investigators Association |
| HTH | Happy To Help / Hope This Helps |
| HTM | HTML Extention |
| HTML | HyperText Mark-up Language |
| HTTP | HyperText Transfer Protocol |
| HTTPD | HyperText Transfer Protocol Daemon |
| HTX | HTML Extention |
| HU | High Usage |
| HUB | Head Up Butt |
| HUTG | High Usage Trunk Group |
| HVAC | Heating Ventilation and Air Conditioning |
| HVM | High Volume Manufacturing |
| HW | HardWare / HRSC-WAOSS |
| HWG | HTML Writers Guild |
| HWS(PEST) | Husband Wants Sex (Please Excuse Slow Typing) |
| HWSPEST | Husband Wants Sex (Please Excuse Slow Typing) |
| HYCFAPMSFTJ | Honestly you couldn't find a person more suited for the job. |
| HZ | Hertz (usually as Hz) |
H
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
