Every counter-strike player would be the awnser to the question. Console commands are necessary to set-up the crosshair, viewmodel, training etc. In this guide I'll try to go as in-depth as I can, to help both beginners and veterans. More commands might be added, and I'm open to suggestions in the comments!

CS:GO is based on the source engine, some of these commands may apply to other source games like Half-Life 2 and Team Fortress 2.

Russian version by TwoKey

• Guide was created

• Added Bind, Alias, Admin and Bot Commands

• Russian version created by TwoKey

• Added HUD/UI Commands and Changelog

• Added kevlar, kevlar helm and zeus to the Weapon Codes under Cheats section
  
• Changed "Movement commands" to "Player commands"
  
• Added "buy" to Player commands
  //Sorry for no updates ;)

Ok, since we're dealing with a developer console, there's a language to it as well. For example the command nomenclature for the map command is:

map <map code>

The <map code> is variable, you may change it to whatever you need to.
Example:

map de_dust2

NOTE: in commands like banid <minutes> {message}, the variable inside the {} is optional, the command will work without it!

To enable the console you have to follow these steps:

• 1 - Open the options menu
  
• 2 - Open "Game Settings"
  
• 3 - Toggle "Enable Developer Console(~)"

Now that the console is enabled all you have to do to get it open is pressing the "~" on your keyboard, that key changes its place on every keyboard language settings, on english keyboards, it positions itself below the escape key.

Alternative Way (Video):

Command: sv_cheats <state>

sv_cheats allows all players in the server to have acess to all console commands. This will disable achievements on the server.

This command is very important for training configs and console commands in general.

Commands: map <map code>

To load maps using the console you may use the "map" command.

Examples: map de_dust2

What are the "map codes" ?

Valve's dev console has an autocomplete function, so you just need to type in the console "map " and all possible maps will be listed. You can use the keyboard arrow keys to navigate through the maps.

NOTE: Maps that end with "_se" are modified versions of the maps that were created for competitive play by removing dust particles, unwanted sounds, etc.

NOTE²: Maps that start with "de_" are defuse and demolition maps, maps that start with "cs_" are hostage maps, maps that start with "ar_" are arms race maps and maps that start with "gd_" are guardian maps.

Commands:
+jump
+duck
+forward
+lookup
+lookdown
+left
+back
+right
+attack
+attack2
+reload
buy <weapon code>
drop

+jump - makes you jump
+duck - makes you crouch
+forward - makes you go forward
+lookup - makes you look up
+lookdown - makes you look down
+left - makes you move left
+back - makes you move backwards
+right - makes you move right
+attack - makes you use your primary
+attack2 - makes you use your secondary attack
+reload - makes you reload
buy - buys the weapon/item listed in the command argument. Refer to the weapon codes under "cheats" to find them
drop - drops the current active weapon

To stop any of these you may use - instead of a + on the start.

Commands:
bind <key> <commands>
alias <name> <commands>

bind - binds commands to a key on the keyboard or mouse. You have to use ; to separate commands.

Example:
bind f "noclip;give weapon_ak47"

Note: The quotes are only necessary if you want to use more than 1 command.

alias - with this commands you can make your own commands by combining other commands.

Example:
alias training "sv_cheats 1;sv_infiniteammo 2;give weapon_flashbang;give weapon_hegrenade;give weapon_smokegrenade;give weapon_ak47"

With this alias, every time you type "training" on the console, it will execute all the commands listed.

Note: Commands aren't the only thing you can use bind on, it also works with aliases.

Commands:
safezonex <pixels>
safezoney <pixels>
hud_scaling <scale>
cl_hud_radar_scale <scale>
cl_hud_background_alpha <alpha>
cl_hud_bomb_under_radar <state>
cl_radar_icon_scale_min <scale>
cl_radar_rotate <state>
cl_radar_scale <scale>
cl_hud_color <color code>
cl_hud_healthammo_style <state>
cl_hud_playercount_pos <state>
cl_hud_playercount_showcount <state>
cl_draw_only_deathnotices <state>


safezonex - sets how close the HUD is to the middle of the screen (x axis).
safezoney - sets how close the HUD is to the middle of the screen (y axis).
hud_scaling - sets the size of the entite HUD (Default 0.85; Min 0.50; Max 0.95)
cl_hud_radar_scale - sets the size of the radar (Default 1.0; Min 0.82; Max 1.30)
cl_hud_background_alpha - Sets the transparency of the radar (Deault 0.5 ; Max 1.0)
cl_hud_bomb_under_radar - if set to 1 a bomb icon will appar under the radar when picked up
cl_radar_icon_scale_min - sets the size of icons in the radar (Min 0.4;Max 1.0)
cl_radar_rotate - Dictates whether or not the radar rotates with player movement (On 1;Off 0)
cl_radar_scale - Sets the "zoom" of the radar (Min 0.25; Max 1.0)
cl_hud_color - sets the color of the hud (color code reference on the bottom of guide)
cl_hud_healthammo_style - sets the style for the health/ammo bars (0 or 1)
cl_hud_playercount_pos - sets the match status HUD position (0 is top;1 is bottom)
cl_hud_playercount_showcount - sets the player boxes UI type (0 shows avatars;1 shows count)
cl_draw_only_deathnotices - if set to 1 will disable most of the UI

Aqua - 1
Green - 2
Yellow - 3
Orange - 4
Red - 5
Pink - 6
Purple - 7
Blue - 8
Light Blue - 9
White - 10

Commands:
god
gods
sv_infinite_ammo <state>
noclip
r_drawothermodels <state>
give <weapon code>

god - gives the player god mode (invincibility)
gods - give all the players god mode (invincibility)
sv_infinite_ammo - if state is set to 1 you'll never have to reload again, if state is set to 2 you'll have infinite magazines
noclip - will make you fly and clip through walls
r_drawothermodels - sets the player visibilities (0=hide all players, 1=normal, 2=see through walls)
give - gives a weapon to the player you may use weapon codes ONLY

Pistols
Desert Eagle: weapon_deagle
Dual Berettas: weapon_elite
Five-Seven: weapon_fiveseven
Glock-18: weapon_glock
p250: weapon_p250
USP-S: weapon_usp_silencer
Tec-9: weapon_tec9
P2000: weapon_hkp2000

SMGs
MP9: weapon_mp9
MAC-10: weapon_mac10
MP7: weapon_mp7
P90: weapon_p90
PP-Bizon: weapon_bizon
UMP-45: weapon_ump45

Heavy
Nova: weapon_nova
XM1014: weapon_xm1014
Mag-7: weapon_mag7
Sawed-off: weapon_sawedoff
Negev: weapon_negev
m249: weapon_m249

Rifles
Ak-47: weapon_ak47
Galil-AR: weapon_galilar
Sg-556: weapon_sg556
Famas: weapon_famas
M4A4: weapon_m4a1
M4A1-S: weapon_m4a1_silencer
AUG: weapon_aug
Scout: weapon_ssg08
AWP: weapon_awp
G3SG1: weapon_g3sg1
SCAR-20: weapon_scar20

Grenades
High Explosive Grenade: weapon_hegrenade
Flashbang: weapon_flashbang
Smoke Grenade: weapon_smokegrenade
Decoy: weapon_decoy
Molotov: weapon_molotov
Incediary Grenade: weapon_incgrenade

Others
Zeus x27: weapon_taser
Kevlar: item_kevlar
Kevlar + Helm: item_assaultsuit

NOTE: Knives can be spawned, but they'll be dropped to the ground. The command only gives you the item, it doesn't remove the knife you have and equip the new one! Console commands cannot remove items and equip.

Thats all of them!

Commands:
bot_add {bot name}
bot_add_ct {bot name}
bot_add_t {bot name}
bot_kick {bot name}
bot_kill {bot name}
bot_zombie <state>
bot_dont_shoot {bot name}
bot_difficulty <difficulty>

bot_add : adds a bot to the team with player disavantage (bot name is optional)
bot_add_ct: adds a bot to ct team (bot name is optional)
bot_add_t: adds a bot to t team (bot name is optional)
bot_kick: if bot name isn't specified, it kicks all bots
bot_kill: if bot name isn't specified, kills all bots
bot_zombie: if set to "1" will freeze all bots
bot_dont_shoot: if bot name isn't specified, all bots won't shoot
bot_difficulty: changes the AI level of the bots(difficulty levels: 0=easy, 1=normal, 2=hard)

These are some of the most important console commands for every csgo player. They allow control over the match settings, perfect for people looking to train and server admins!

Commands:
mp_limitteams <state>
mp_autoteambalance <state>
mp_roundtime <time in minutes>
mp_roundtime_defuse <time in minutes>
mp_maxmoney <ammount of money>
mp_startmoney <ammount of money>
mp_freezetime <time in seconds>
mp_buytime <time in seconds>
mp_buy_anywhere <state>
ammo_grenade_limit_total <ammount of grenades>
mp_restartgame <time in seconds>
mp_ignore_round_win_conditions <state>

mp_limitteams - with this set to 0 there will be no limit to ammout of people in the teams
mp_autoteambalance - with this set to 0, there will be no auto-bancing
mp_roundtime - set the time of the rounds (max:60 mins)
mp_roundtime_defuse - set the time of the rounds (max:60 mins)
mp_maxmoney - set maximum money
mp_startmoney - set starting money
mp_freezetime - sets the time that the players are frozen on the start of the round
mp_buytime - sets the time to buy
mp_buy_anywhere - if set to 1, you may buy wherever you want
ammo_grenade_limit_total - changes the max grenade limit
mp_restartgame - restarts the match
mp_ignore_round_win_conditions - if set to 1, the server will ignore the conditions that end the round

Commands:
sv_grenade_trajectory <state>
sv_showimpacts <state>

sv_grenade_trajectory - shows the trajectory made by a grenade
sv_showimpacts - shows where your bullets hit (blue boxes are what the server sees, red boxes are what the client sees)

Commands:
kick <name>
kickid <steam id> {message}
kickid_ex <steam id> <force> {message}
banid <minutes> <steam id> {kick}
banip <minutes> <ip adress>
addip <minutes> <ip adress>

NOTE: banip and addip do the same thing!!!

kick - kicks player from server
kickid - kick player by steam id message is optional
kickid_ex - kicks by steam id, has force modifier(0 or 1) message is optional
banid - bans steam id, set <minutes> to 0 for permanent ban
banip - bans ip adress, set <minutes> to 0 for permanent ban
addip - bans ip adress, set <minutes> to 0 for permanent ban

Thanks for reading through my guide, if you liked it, please rate and favorite it, this is my first guide so I can't do a shameless plug here... or can I? If you want a recommendation, you can watch BananaGaming they do pretty great videos on counter-strike!
This guide will be fixed and expanded as time goes on. Please tell me in the comments if you find anything that could be changed/fixed!

Credits:
SliQ helping with typos and text revision