RPi can be used as a Wi-Fi Access Point.
While acting as an Access Point, the Wi-Fi interface can also accept connections. Meaning, the device can also serve as a host without additional configuration (i.e. for SSH access).
To set up, follow the Acces Point article in the Linsk section below.
Once the RPi acts as an Access Point it is useful to configure network routing.
To enable access point functionality, edit "/etc/hostapd/hostapd.conf" as per instructions. I.e.
interface=wlan0driver=nl80211ssid=NameOfNetworkhw_mode=gchannel=7wmm_enabled=0macaddr_acl=0auth_algs=1ignore_broadcast_ssid=0wpa=2wpa_passphrase=AardvarkBadgerHedgehogwpa_key_mgmt=WPA-PSKwpa_pairwise=TKIPrsn_pairwise=CCMP