Network speeds in bits. ISPs advertise in Mbps, Gbps. 100 Mbps internet, 1 Gbps fiber. Marketing uses bits because numbers look bigger! 8 bits = 1 byte, so actual download speed is 1/8 the advertised.

• Kbps, Mbps, Gbps (bits)
• ISP advertised speeds
• Looks bigger (marketing)
• Divide by 8 for bytes

Actual transfer speed. Downloads show MB/s, GB/s. 100 Mbps internet = 12.5 MB/s download. Always 8x smaller than bits. This is the REAL speed you get!

• KB/s, MB/s, GB/s (bytes)
• Actual download speed
• 8x smaller than bits
• What you really get

Real-world tech specs. WiFi 6 (9.6 Gbps), 5G (10 Gbps), Thunderbolt 5 (120 Gbps), 400G Ethernet. These are THEORETICAL maximums. Real-world speeds 30-70% of rated due to overhead, congestion, distance.

• Theoretical maximums
• Real = 30-70% of rated
• WiFi, 5G, USB, Ethernet
• Overhead reduces speed

Internet providers use Mbps, Gbps. 100 Mbps package, 1 Gbps fiber. Bits make numbers bigger! 1000 Mbps sounds better than 125 MB/s (same speed). Marketing psychology.

• Mbps, Gbps (bits)
• ISP packages
• Bigger numbers
• Marketing trick

What you actually see. Steam, Chrome, uTorrent show MB/s. 100 Mbps internet downloads at 12.5 MB/s max. Always divide ISP speed by 8 for real download speed.

• MB/s, GB/s (bytes)
• Download managers
• Divide ISP by 8
• Real speed shown

WiFi, Ethernet, USB, 5G specs. WiFi 6: 9.6 Gbps theoretical. Real: 600-900 Mbps typical. 5G: 10 Gbps theoretical. Real: 500-1500 Mbps typical. Specs are lab conditions, not real-world!

• WiFi, 5G, USB, Ethernet
• Theoretical vs real
• Overhead matters
• Distance degrades

Data needs headers, error correction, acknowledgments. TCP/IP adds 5-10% overhead. WiFi adds 30-50% overhead. Ethernet adds 5-15%. Real throughput always less than rated. 1 Gbps Ethernet = 940 Mbps max usable.

• TCP/IP: 5-10% overhead
• WiFi: 30-50% overhead
• Ethernet: 5-15% overhead
• Headers reduce speed

WiFi weakens with distance, walls. At 1m: 90% of rated. At 10m: 50% of rated. Through walls: 30% of rated. 5G similar. mmWave 5G blocked by walls completely! Physical barriers kill speed.

• Distance reduces signal
• Walls block WiFi
• 5G mmWave: wall = 0
• Closer = faster

Network capacity shared among users. Home WiFi: all devices share. ISP: neighborhood shares. Cell tower: everyone nearby shares. More users = slower for each. Peak hours slowest!

• Shared among users
• More users = slower
• Peak hours worst
• Not dedicated speed

Typical packages: 100 Mbps (12.5 MB/s), 300 Mbps (37.5 MB/s), 1 Gbps (125 MB/s). Streaming 4K: needs 25 Mbps. Gaming: needs 10-25 Mbps. Video calls: 3-10 Mbps.

• 100 Mbps: basic
• 300 Mbps: family
• 1 Gbps: power users
• Match to usage

Offices: 1-10 Gbps. Data centers: 100-400 Gbps. Cloud: Tbps. Business needs symmetric speeds.

• Office: 1-10 Gbps
• Data center: 100-400 Gbps
• Symmetric
• Massive bandwidth

4G: 20-50 Mbps. 5G: 100-400 Mbps. mmWave: 1-3 Gbps (rare). Location dependent.

• 4G: 20-50 Mbps
• 5G: 100-400 Mbps
• mmWave: 1-3 Gbps
• Varies wildly

Divide by 8. 100 Mbps / 8 = 12.5 MB/s. Quick: divide by 10.

• Mbps / 8 = MB/s
• 100 Mbps = 12.5 MB/s
• 1 Gbps = 125 MB/s
• Quick: / 10

Size / speed = time. 1 GB at 12.5 MB/s = 80 sec.

• Size / speed = time
• 1 GB @ 12.5 MB/s = 80s
• Add 10-20% overhead
• Real time longer

300 Mbps internet. Real download?

300 / 8 = 37.5 MB/s theoretical. With overhead: 30-35 MB/s real. That's normal!

50 GB game, 200 Mbps. How long?

200 Mbps = 25 MB/s. 50,000 / 25 = 2,000 sec = 33 min. Add overhead: 37-40 min.

WiFi 6 vs 10G Ethernet?

WiFi 6 real: 600 Mbps. 10G Ethernet real: 9.4 Gbps. Ethernet 15x+ faster!

56K modem: 7 KB/s. 1 GB = 40+ hours! Gigabit = 18,000x faster. Day's download now takes 8 seconds.

5G mmWave: 1-3 Gbps but blocked by walls, leaves, rain, hands! Stand behind tree = no signal.

120 Gbps = 15 GB/s. Copy 100 GB in 6.7 sec! Faster than most SSDs. Cable faster than drive!

46 Gbps theoretical, 2-5 Gbps real. First WiFi faster than most home internet! WiFi becomes overkill.

1990s: 56 Kbps. 2020s: 10 Gbps home. 180,000x speed increase in 30 years!

Data transmission began not with computers, but with Morse code clicking across wires. The telegraph proved that information could travel faster than physical messengers.

• **Morse Telegraph** (1844) - ~40 bits per minute via manual keying. First long-distance data network.
• **Teleprinter/Teletype** (1930s) - 45-75 bps automated text transmission. News wires and stock tickers.
• **Early Computers** (1940s) - Punch cards at 100-300 bps. Data moved slower than a person could read!
• **Modem Invention** (1958) - 110 bps over phone lines. AT&T Bell Labs enables remote computing.

The telegraph established the fundamental principle: encode information as electrical signals. Speed was measured in words per minute, not bits—the concept of 'bandwidth' didn't yet exist.

Modems transformed every phone line into a potential data connection. The screech of a 56K modem connected millions to the early internet, despite agonizing speeds.

• **300 bps Acoustic Couplers** (1960s) - Literally held phone to modem. Could read text faster than download!
• **1200 bps Modems** (1980s) - BBS era begins. Download a 100KB file in 11 minutes.
• **14.4 Kbps** (1991) - V.32bis standard. AOL, CompuServe, Prodigy launch consumer internet.
• **28.8 Kbps** (1994) - V.34 standard. Email with small attachments becomes feasible.
• **56K Peak** (1998) - V.90/V.92 standards. Theoretical maximum of analog phone lines reached. 1 MB = 2.4 minutes.

56K modems rarely achieved 56 Kbps—FCC limited upstream to 33.6K, line quality often limited download to 40-50K. Every connection was a negotiation, accompanied by that iconic screech.

Always-on connections replaced dial-up's patience test. Cable and DSL brought 'broadband'—initially just 1 Mbps, but revolutionary compared to 56K.

• **ISDN** (1990s) - 128 Kbps dual-channel. 'It Still Does Nothing'—too expensive, arrived too late.
• **DSL** (1999+) - 256 Kbps-8 Mbps. Copper phone lines repurposed. Asymmetric speeds begin.
• **Cable Internet** (2000+) - 1-10 Mbps. Shared neighborhood bandwidth. Speed varied wildly by time of day.
• **Fiber to the Home** (2005+) - 10-100 Mbps symmetric. First true gigabit-capable infrastructure.
• **DOCSIS 3.0** (2006) - Cable modems reach 100+ Mbps. Multiple channels bonded together.

Broadband transformed internet use. Streaming video became possible. Online gaming went mainstream. Cloud storage emerged. The 'always-on' connection changed how we lived online.

Smartphones demanded mobile data. WiFi freed devices from cables. Wireless speeds now rival or exceed wired connections of a decade ago.

• **3G** (2001+) - 384 Kbps-2 Mbps. First mobile data. Painfully slow by modern standards.
• **WiFi 802.11n** (2009) - 300-600 Mbps theoretical. Real: 50-100 Mbps. Good enough for HD streaming.
• **4G LTE** (2009+) - 10-50 Mbps typical. Mobile internet finally usable. Killed need for mobile hotspots.
• **WiFi 5 (ac)** (2013) - 1.3 Gbps theoretical. Real: 200-400 Mbps. Multi-device homes become feasible.
• **WiFi 6 (ax)** (2019) - 9.6 Gbps theoretical. Real: 600-900 Mbps. Handles dozens of devices.
• **5G** (2019+) - 100-400 Mbps typical, 1-3 Gbps mmWave. First wireless faster than most home broadband.

WiFi 7 (2024): 46 Gbps theoretical, 2-5 Gbps real. Wireless is becoming faster than wired for the first time in history.

While consumers celebrated gigabit, datacenters operated at scales unimaginable to most: 100G, 400G, and now terabit Ethernet connecting server racks.

• **10 Gigabit Ethernet** (2002) - 10 Gbps wired. Enterprise backbone. Cost: $1000+ per port.
• **40G/100G Ethernet** (2010) - Datacenter interconnects. Optics replace copper. Port cost drops to $100-300.
• **Thunderbolt 3** (2015) - 40 Gbps consumer interface. USB-C connector. Fast external storage goes mainstream.
• **400G Ethernet** (2017) - 400 Gbps datacenter switches. Single port = 3,200 HD video streams.
• **Thunderbolt 5** (2023) - 120 Gbps bidirectional. Consumer cable faster than most server NICs from 2010.
• **800G Ethernet** (2022) - 800 Gbps datacenter. Terabit ports incoming. Single cable = entire ISP's neighborhood capacity.

A single 400G port transfers 50 GB/second—more data than an entire 56K modem could transfer in 2.5 years of continuous operation!

Speed plateaus for consumers (gigabit is 'enough'), while infrastructure races toward terabits. The bottleneck shifted from connections to endpoints.

• **Consumer Internet** - 100-1000 Mbps typical. 1-10 Gbps available in cities. Speed exceeds most devices' ability to use it.
• **5G Deployment** - 100-400 Mbps typical, 1-3 Gbps mmWave rare. Coverage more important than peak speed.
• **WiFi Saturation** - WiFi 6/6E standard. WiFi 7 arriving. Wireless 'good enough' for almost everything.
• **Datacenter Evolution** - 400G becoming standard. 800G deploying. Terabit Ethernet on roadmap.

Today's limits: storage speed (SSDs max ~7 GB/s), server CPUs (can't process packets fast enough), latency (speed of light), and cost (10G home connections exist, but who needs them?)

Streaming revolutionized entertainment, but quality demands bandwidth. Understanding requirements prevents buffering and overspending.

• **SD (480p)** - 3 Mbps. DVD quality. Looks bad on modern TVs.
• **HD (720p)** - 5 Mbps. Acceptable on smaller screens.
• **Full HD (1080p)** - 8-10 Mbps. Standard for most content.
• **4K (2160p)** - 25 Mbps. 4x more data than HD. Needs consistent speed.
• **4K HDR** - 35-50 Mbps. Premium streaming (Disney+, Apple TV+).
• **8K** - 80-100 Mbps. Rare. Few have 8K TVs or content.

Multiple streams add up! 4K living room (25 Mbps) + 1080p bedroom (10 Mbps) + 720p phone (5 Mbps) = 40 Mbps minimum. 100 Mbps internet recommended for family of 4.

Gaming demands low latency more than high bandwidth. Cloud gaming changes the equation dramatically.

• **Traditional Online Gaming** - 3-10 Mbps sufficient. Latency matters more!
• **Game Downloads** - Steam, PlayStation, Xbox. 50-150 GB games common. 100 Mbps = 1 hour per 50 GB.
• **Cloud Gaming (Stadia, GeForce Now)** - 10-35 Mbps per stream. Latency < 40ms critical.
• **VR Gaming** - Higher bandwidth + latency critical. Wireless VR needs WiFi 6.

Ping matters more than speed! 5 Mbps with 20ms ping beats 100 Mbps with 80ms ping for competitive gaming.

Video calls and cloud access became essential post-2020. Upload speed finally matters!

• **Zoom/Teams Video** - 2-4 Mbps down, 2-3 Mbps up per stream.
• **HD Video Conferencing** - 5-10 Mbps down, 3-5 Mbps up.
• **Screen Sharing** - Adds 1-2 Mbps up.
• **Cloud File Access** - Depends on files. 10-50 Mbps typical.
• **VPN Overhead** - Adds 10-20% latency and overhead.

Cable internet often has 10x slower upload! 300 Mbps down / 20 Mbps up = one video call maxes upload. Fiber's symmetric speeds critical for work-from-home.

Behind every app and website, servers move data at scales hard to comprehend. Speed directly equals money.

• **Web Server** - 1-10 Gbps per server. Handles thousands of concurrent users.
• **Database Server** - 10-40 Gbps. Storage I/O bottleneck, not network.
• **CDN Edge Node** - 100 Gbps+. Serves video to entire region.
• **Datacenter Spine** - 400G-800G. Aggregates hundreds of racks.
• **Cloud Backbone** - Terabits. AWS, Google, Azure private networks exceed public internet.

At scale, 1 Gbps = $50-500/month depending on region. 400G port = $20,000-100,000/month at some providers. Speed is expensive!

Wireless speeds now compete with home broadband. But cell towers share bandwidth among all nearby users.

• **4G LTE** - 20-50 Mbps typical. 100+ Mbps in ideal conditions. Slows during rush hour.
• **5G Sub-6GHz** - 100-400 Mbps typical. Better than most home connections. Wide coverage.
• **5G mmWave** - 1-3 Gbps in rare ideal conditions. Blocked by walls, trees, rain, hands. 100m range max.
• **Tower Capacity** - Shared! 1000 users on tower = 1/1000 of capacity each during peak.

Wireless speeds vary wildly by location, time of day, and nearby users. Tower 200m away = 10x slower than tower 20m away.

Correct! 100 Mbps / 8 = 12.5 MB/s. ISPs use bits, downloads use bytes. You get what you paid for!

Real-world: WiFi 6 = 600-900 Mbps. 5G = 100-400 Mbps typical. WiFi wins at home!

4K: 25 Mbps. Family of 4: 100 Mbps. 8+ devices: 300 Mbps. Power users: 1 Gbps.

Wireless = 50-70% of rated. Wired = 94%. Overhead, interference, distance hurt WiFi.

Download: receiving. Upload: sending. ISPs advertise download, upload 10-40x slower!