It's important to note that Ireland issues its own visas. While it is part of the European Union, the country is one of few that are not covered by the Schengen visa. So even if you applied for one, it won't help you get into Ireland. You might also mistake the country as still part of the British Isles. Not only is this no longer true but doing so is considered rude and insulting to the Irish. Therefore, no, a British visa will also not give you entry to Ireland. You'll have to apply for a separate Irish visa and you can do so online.
As already mentioned, Ireland is a part of the EU. And while a Schengen visa won't grant you entry into the country. being a citizen of a fellow member-nations does. If you're a citizen of any EU country, you'll only need to show your passport and identity card and you're good to go. Though this privilege only lasts the same period of time as a short-term tourist Irish visa, which is 90 days or approximately three months. The Short Stay Visa Waiver Programme also allows citizens of certain countries who have UK visas to also get to entire Ireland without a separate Irish visa. But because of the COVID-19 pandemic, this program is currently suspended.
As with any other visa application, you start by gathering and showing some needed documents to accompany your filled-up application form. They include your valid passport, a passport photo, proof of funds, and if applicable, details of relatives residing in Ireland or any other EU country as well as previous applications for an Irish visa. For your passport, ensure that it remains valid for six months after your departure date to Ireland. It must also have at least two blank visa pages and others that show other visas that you've been granted with. For your proof of funds, bank statements will do.
You will also need to show full details of your reason for visiting Ireland and documents to support your claim. For instance, if you were invited to come here for a seminar, include the invitation letter to the said seminar in the list of documents you'll show the Irish embassy in your country. Also, if you can provide a reference that invited you to go to Ireland, have them write a letter detailing why they invited you to travel to the country. The letter should include your reference's contact details, dates of your trip, and it should confirm your relationship with him/her.
Fortunately, the price for applying for a short-term tourist Irish visa isn't that expensive. For a single journey visa, it will only cost you €60.00 (or $72.00). While for a multiple-entry short-term Irish via, the fee is €100.00 (or $120.00). Of course, spouses/partners that are EU citizens need not pay any fee at all. Also, at times, applicants from certain countries don't have to pay application fees. The list changes from time to time to stay updated with your country's Irish embassy to know if you're included on this list.
Once you've entered Ireland with your tourist visa, will you be able to extend your stay while you're already there? The answer is, unfortunately, no. Ireland is rather strict with their visa laws. In fact, the duration of your stay doesn't even depend on the visa you've been ranted, but rather to the immigration border patrol officer who gets to decide if you'll be granted entry to the country or not. You have to adhere to the time period of stay they give you and if you intend to extend, you'll have to go back to your home country and re-apply for another Irish visa.
If you ever plan on going to Ireland, know that you'll need to get an Irish visa to enter the country. They're rather strict with their borders so you'll have to follow the procedure carefully and give everything that's needed for the application.
While planning for your trip, pick a luxurious Irish rental for your accommodation. It'd be a great choice for your stay here!