I’ve ordered the Esp8266 in the form factor or model „03“ which has no standard 2,54mm pin headers. If you want to use it with a breadboard, you’ll need to solder an adapter.
Currently there are 12 different form factors of the Esp8266 available (e.g. here. Not counting sets and development kits). Each version has its own advantages and disadvantages in regards to features, pinouts, form and size. To be most flexible I’ve ordered model „03“, as also posted here as it has the highest number of I/O pins.
The small size results in incompatibility to the standard 2,54 pin header spacing. To fix this I soldered it on a PCB with normal pin headers below. I was generous with the size of the PCB. It’s possible to squeeze it to 4×7 holes. But I’ve never done something like that before and didn’t know how good the wires could be soldered.
Here are the steps: